With all of the extensive troubleshooting and debugging that I have done over the last year for OAB generation process, I thought it would be worth while to write an tool that could help customers troubleshoot these issues. The OAB generation process is unknown to many, so I have felt the need to starting posting about it.
This tool is now being used extensively by some of the biggest premier enterprise and hosting customers in the US and in Europe. I am glad to say that this tool is now available for download, and is no longer an internal only support tool.
There is also a public kb article for the tool http://support.microsoft.com/?id=907792 – Description of the Offline Address Book Integrity (OABInteg) tool.
There is also a public kb article for the tool http://support.microsoft.com/?id=907792 – Description of the Offline Address Book Integrity (OABInteg) tool.
The tool can be downloaded from the following location: http://code.msdn.com/oabinteg
I want to thank two people for posting documentation on OABInteg.
2. Matt Richoux who created the webcast on “How to troubleshoot Offline Address Book issues in Microsoft Exchange Server”. This web cast contains information on OABInteg and it’s usage. If you missed this web cast, you can go here for more information: http://support.microsoft.com/default.aspx?scid=kb;en-us;905482.
This document covers the Offline Address Book Integrity (OABINTEG) tool, which can be very useful for troubleshooting Offline Address Book (OAB) generation issues on the Microsoft Exchange Server, and OAB download problems on the Microsoft Outlook client. OABINTEG uses non-intrusive methods to gather information regarding the following objects:
- Active Directory Address List, Offline Address Lists and Address List related properties
- System Folders
- OAB Messages
- OAB Attachments
- Address List Hierarchy
- Address Book Recipients and data
The tool simulates the following:
- The process a Microsoft Outlook client uses to connect to a public information store to download the OAB files.
- The method the OABGEN process uses to connect to the public information store to perform a rebuild of the OAB. For more information on the rebuild process, please see the “More Information on the OABGen Process” section later in this document.
OABInteg performs the following tests: (Blue – Active Directory Tests & Green – Mapi Tests)
Validate if the information stores point to an address list
List all address lists in the organization
List all offline address lists in the organization
List the address book roots
Scan for users that will be skipped during the OABGEN process
Scan for all legacyExchangeDN’s that have a final RDN greater than 64 characters
Scans the active directory for orphaned display templates
Logon to the public information store and check the OAB system folders, messages and attachments
Displays all of the address book entries from a profile and prints them out with the OAB Version 2 details.
Displays all of the address book entries from a profile and prints them out with the OAB Version 3a details.
Displays all of the address book entries from a profile and prints them out with the OAB Version 4 details.
Displays the Offline Address List hierarchy from the selected public folder information store. Displays all folders and EntryID’s for all folders objects under the Offline Address List folder.
Retrieve all MAPI profiles and read the last known downloaded OAB sequence number.
Will scan the mapisvc.inf file for invalid attributes that can cause OAB Generation to fail.
Constructs a PDN table from the active directory objects.
Performs all the LDAP tests against the active directory | [storealtest] [altest] [oaltest] [abrtest] [proxytest] [templatetest]
WARNING: If you are going to run any of the MAPI
OABINTEG will automatically create a profile called OABInteg-Admin-[TimeStamp] in HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles, and will delete the profile when the tool has completed successfully.
This is useful when there are no existing profiles on the machine.
OABINTEG reports the status of the following in the display output:
- Online or offline status of the information store.
- EntryID used by the profile to open the OAB system folders.
- Replica server for the system folders.
- GUID of the OAB Container.
- OAB attachment number.
- Create date/time stamp of OAB messages and attachments.
- OAB System Folder Hierarchy List and EntryID’s for each folder.
OABINTEG reports the following counters in the display output:
MAPI Test Related
- Message Class Normal found
- Message Class Differential found
- Message Class Unknown found
- Message Attachments found:
- Messages found but unable to read the properties
- System folders found
- Highest sequence number found
- Lowest sequence number found
- Biggest attachment found (in Bytes, MB & GB)
- Smallest attachment found (in Bytes, MB & GB)
- Biggest message found (in Bytes, MB & GB)
- Smallest message found (in Bytes, MB & GB)
- Total number of entries processed in the address book
- Total information store address lists found
- Total address lists found
- Total offline address lists found
- Total AddressBookRoots objects found
- Total orphaned templates found in the Lost and Found container
- Total contacts found
- Total groups found
- Total user mailboxes found
- Total user objects that match primary proxy and mail attribute
- Total user objects that do not match primary proxy and mail attribute
- Total user objects that are missing one or both attributes
- Total user objects that are missing the Primary Proxy address attribute
- Total user objects with vaild Domain values
- Total user objects with invalid Domain values
- Total user objects SMTP Domain missing
- Total user objects with SMTP Domain present
- Total user objects with valid legacyExchangeDN attribute
- Total user objects with temp legacyExchangeDN’s
- Total user objects with invalid legacyExchangeDN attribute
- Total user objects with proxy addresses equal to or over 64 characters
- Total objects that have RDN’s that ok
- Total objects that have RDN’s that are greater than 64 characters
- Total PDN’s found
- Debug Info – PDN Strings inserted into the PDN table:
- Debug Info – X500 entries skipped because they are NULL. This is valid and ok
- Debug Info – Duplicate PDN strings not inserted into the PDN table
OABINTEG Command-Line Parameters
The OABINTEG tool has the following parameters:
Usage: OABInteg.exe [/s:servername] [/t:testname] [/l] (enable file logging) [/v: 1,2 or 3] (1 = minimum | 2 = maximum logging | 3 = ErrorsOnlyLogging
Optional Commands [/d:OUSearchDN] [/p:# – Page Size] [/U:UserName] [/P:Password] [/r:Alias]
[/l] Logging output will go to c:\OABInteg.txt
[/v] Logging output will go to the screen. – Default logging is general – /v:1 for minimum | /v:2 for maximum logging. | /v:3 for ErrorsOnlyLogging (Proxytest only)
[/p:] Active Directory search page size. Default size is 64 and maximum is 512.
[/dn:] LDAP test only!! <Example: OU=Managers,DC=OrgName,DC=local>
NOTE: If you do not specify a search /dn: we will use base query of DC=OrgName,DC=local
[/U:] Username. If you are going to connect use different credentials or connect to a different domain.
[/P:] Password. If you are going to connect use different credentials or connect to a different domain.
[/r:] Alias. If you want to return one object from the Global Address List for any mapi test use this command.
Active Directory Tests
[storealtest] – Validate if the information stores point to an Address list.
[altest] – Finds all address lists in the organization.
[oaltest] – Finds all offline address lists in the organization.
[abrtest] – Finds the addressBookroots properties.
[rdntest] – Scan for all legacyExchangeDN’s that have a final RDN greater than 64 characters.
[templatetest] – Scans the active directory for any orphaned display templates.
[alltests] – Runs all the LDAP tests | [-storealtest][-altest][-oaltest][-abrtest][-rdntest][-templatetest].
[proxytest] – Scan for users that will be skipped during the oabgen process. <Checks for invalid legacy Dn’s also>
[oabfldcheck] – Logon to the public information store and check the OAB system folders, messages and attachments.
[getabinfo_v2] – Open the default address book for a selected profile and dump all entries using OAB V2 props.
[getabinfo_v3] – Open the default address book for a selected profile and dump all entries using OAB V3a props.
[getabinfo_v4] – Open the default address book for a selected profile and dump all entries using OAB V4 props.
[hierarchylist] – Logon to the public information store and get the OAB Hierarchy list information.
[dumpPDNtable] – Uses a MAPI profile to connect to the Active Directory and creates a PDN table.
[oabsizer_v3] – Calculates the size for GAL objects using the oab_v3a properties.
[oabsizer_v4] – Calculates the size for GAL objects using the oab_v4 properties.
[getoabseqnum] – Check all user profiles and find the last downloaded OAB sequence number.
Mapi File Tests
[scanmapisvc] – Scan the mapisvc.inf file for invalid values.
[proxytest] – Should be ran using an Online profile from the exchange server or client.
[oabfldcheck] – Can be run (1. on the exchange server or 2. from a client.)
[hierarchylist] – MUST be run against an exchange server from (1. on the exchange server or 2. from a client.)
[getabinfo_v2] – Can be run (1. on the exchange server or 2. from a client.)
[getabinfo_v3] – Can be run (1. on the exchange server or 2. from a client.)
[getabinfo_v4] – Can be run (1. on the exchange server or 2. from a client.)
[oabsizer_v3] – Can be run (1. on the exchange server or 2. from a client.)
[oabsizer_v4] – Can be run (1. on the exchange server or 2. from a client.)
[getoabseqnum] – MUST be run on the outlook client. This test reads from the registry.
[scanmapisvc] – MUST be run on the outlook client. This test reads from the registry and profile.
[dumpPDNtable] – Used a profile to connect to the active directory and creates a PDN table.
NOTE: The LDAP tests ([storealtest] [altest] [oaltest] [abrtest] [proxytest] [rdntest] [templatetest]) can only be performed against a global catalog server.
NOTE: All AD queries are performed on port 3268. If no SearchDN is specified, the default Domain Naming Context container (DC=
Example 1: A typical active directory query uses syntax similar to the following:
oabinteg.exe /s:GCName /t:TestName /d:OU=Managers,DC=
Example 2: To perform a MAPI test from an Exchange Server or Outlook client, run the following syntax: oabinteg.exe /s:ExchangeServerName /t:oabfldcheck
TEST – [storealtest]- Validate Store Offline Address List
Each Microsoft exchange server has a default offline address list associated with it. If this setting is not properly set, it can cause problems when trying to query the exchange system folders. This test will check all of the exchange information stores to see if they have this setting applied.
TEST- [altest]- Address Lists Test
This test will query the CN=Microsoft Exchange active directory object, and extract all of the address lists in the exchange organization. This is useful in determining if there are inconsistencies between active directory domain controllers.
TEST – [oaltest] – Offline Address List Test
This test will query the CN=Microsoft Exchange active directory object, and extract all of the offline address lists in the exchange organization.
TEST – [abrtest]- Address Book Roots Test
Microsoft Exchange configures trees of address book containers to show up in the MAPI address book. This attribute on the Exchange Configuration object lists the roots of the address book container trees. During certain situations (hosting) the entries to the addressBookroots can become mis-configured thus causing problems with rebuilding address lists. This test will pull all of the attributes from the addressBookroots object so they can be compared to the address lists in the organization.
TEST – [proxytest] – Simple Mail Transfer Protocol Address Mismatches and legacyExchangeDN Mismatch
Prior to Service Pack 1 for Exchange Server 2003, company-wide full downloads of the OAB could occur because of Simple Mail Transfer Protocol (SMTP) address mismatches. In an SMTP address problem, a differential update is created, but Outlook cannot correctly parse the update.
All mail-enabled objects (mailbox, contact, and distribution group) in your organization must have a mail attribute and a proxyAddresses attribute. The proxyAddresses attribute must contain a primary SMTP proxy with the same alias as the mail attribute. For example, if the mail attribute is firstname.lastname@example.org, SMTP:email@example.com must reside in the proxyAddresses attribute. A valid primary SMTP proxy must be in the form “SMTP:<alias>@<domain.com>” (not “smtp:”), where alias is the user’s e-mail alias and domain.com is the company’s domain name.
Note: A primary SMTP proxy starts with “SMTP:” (all uppercase) and additional SMTP proxies start with “smtp:” (all lowercase).
Other factors to consider with respect to SMTP addresses include:
- The maximum length of an SMTP relative distinguished name (the portion followed by the at sign (@)) is 63 characters.
- The alias and the domain name must not begin with any of these characters: space, !”#$%&`()*+,-./ or any unprintable character. Domain names typically begin with a letter or number, but mistyping a space at the beginning is a common error.
- The SMTP problem as it relates to OAB downloads affects differential updates only. The user’s Active Directory service entry must be changed to appear in the differential update file. It is possible for the entry to appear in the differential update (as if a change had been made) if there exists another user in your organization who has the same displayName attribute in Active Directory.
In Exchange Server 2003 SP1, SMTP address mismatches no longer create the need for full OAB downloads because the users with the mismatched addresses are not added to the OAB. Instead, when such a user is encountered, the following event is generated in the Application event log of the OAB server:
Event Source: MSExchangeSA
Event ID: 9325
Event Type: Error
Description: OALGen will skip user entry %1 in address list %2 because the SMTP address %3 is invalid.
To determine whether to add a user to an OAB, OABGen performs several validation tasks to determine if the SMTP proxy addresses for each user are correct and not malformed or mismatched. If any of the validation tasks fail, the user is not added to the OAB, and the earlier event log entry is logged.
This will also stand for the legacyExchangeDN attribute. If this attribute does not begin with /=o or /=O we can not verify if this is a valid object and we will skip this user object during the rebuild process.
This test will scan for all user objects to see if they have the correct attributes, if not they will be logged by this application.
This test will also test to see if the objects legacy exchangeDN starts with /o= or /O=. If it does not or is incorrect we will record this.
TEST – [templatetest]- OAB Orphaned Display Templates Test
Detail Template files allow you to see details on mailboxes, custom recipients, or distribution lists. For any reason if the display templates are removed from and you try to generate the default offline address list or any other address list that has been created the offline address list may not be generated on the Exchange server. Event ID 9126 will be logged in the Application event log.
This test will search for orphaned display templates in the Lost and Found container in the AD so that they can be identified and removed.
TEST- [dumpPDNtable] – Dump PDN TableTests
This test will dump out all of the objects that belong to the Default Offline Address List and build a PDN table. This can be used to determine what strings needs to be added or remove to avoid full downloads.
A PDN table is a string table that is maintained by OABGen of PDN’s (Parent Distinguished Names). When the OAB Generation process is generating an address list, it will split the ExchangeLegacyDN and x500 proxy addresses that belong to an object in to two separate parts.
- PDN – Parent Distinguished Name – /o=organization/ou=site/cn=container/
- RDN – Relative Distinguished Name – /cn=dgoldman
This PDN table is used as a reference for the client when it builds MAPI entry ids of mail recipients. Since most recipients in the OAB share the same small set of PDNs, a table was used to save space instead of storing them separately for each recipient. Prior to Exchange 2003 SP2, the OAB Generation process had problems dealing with the addition and removal of PDN’s. Once a PDN table change is detected, it will cause the OAB generation process to skip one day’s differential build..OAB Version 2 and OAB Version 3a clients are affected by this and the ramifications are a full download for the client. With the addition of Exchange 2003 SP2, this is no longer a problem for OAB Version 4 clients.
For more information about this, please refer to this blog: http://blogs.msdn.com/dgoldman/archive/2005/11/18/494545.aspx
TEST- [rdntest] – RDN Size Check Tests
In Exchange Server 5.5, the schema would never let an RDN exceed 64 characters. In Active Directory, the legacyExchangeDN is stored as a free-form string and there is no enforced limit. RDNs greater than 64 characters can cause changes in the way the OAB diff files get applied to a Microsoft Outlook client. In turn, this can cause Outlook to initiate a full OAB download.
TEST- [getabinfo_v2] – Get Offline Address List with OAB Version 2 Properties
This test will allow you to pull the default address list from a profile and download all of the address list entries. All of the entries that are retrieved and displayed with be with the OAB Version 2 properties.
TEST- [getabinfo_v3] – Get Offline Address List with OAB Version 3a Properties
This test will allow you to pull the default address list from a profile and download all of the address list entries. All of the entries that are retrieved and displayed with be with the OAB Version 3a properties.
TEST- [getabinfo_4] – Get Offline Address List with OAB Version 4 Properties
This test will allow you to pull the default address list from a profile and download all of the address list entries. All of the entries that are retrieved and displayed with be with the OAB Version 4 properties.
TEST- [hierarchylist] – Display Public Information Store Offline Address List Hierarchy
This test will connect to the exchange servers public folder information store and get the hierarch list and folder properties from each child folder in the list. The properties that are returned are as follows:
TEST- [getoabseqnum] – Display the oab sequence number from all the profile on a system
This test will open the profiles table on a computer and scan for all of the profiles and extract the last downloaded oab file. This will contain the more recent oab sequence number.
TEST- [scanmapisvc] – Scans the MAPISVC.INF file for invalid entries
This test must be ran on the local system that you want scanned. This will scan the mapisvc.inf file for invalid entries that can cause profile generation problems. Invalid entries can lead to OAB generation problems.
TEST – [oabfldcheck] – OAB System Folder Check Test
The [oabfldcheck] test MUST be run on a Microsoft Exchange Server 2000 or 2003 server or a workstation with the Microsoft Outlook client installed.If you are going to run OABInteg on an Exchange 2007 server, the Microsoft Exchange server must have the following requirements:
1. A Public Folder Store
2. Outlook 2003 or 2007 installed or the Standalone MAPI/CDO install which can be found here: http://blogs.msdn.com/dgoldman/archive/2006/06/19/636996.aspx. For more information on why you need to install Outlook or the standalone MAPI/CDO install please reference this: http://blogs.msdn.com/dgoldman/archive/2007/02/27/installing-outlook-2007-on-an-exchange-2007-server.aspx
NOTE: By default this test with general logging will not display any of the test results, only the counters at the end of the test. As this test is running you might see the screen scrolling down, and this is normal. This was done for performance reasons while running through a command window. If you want to see all of the test results, please use the /v2 command line parameter at the end of your command line syntax (Example: oabinteg.exe /s:ExchSrvrName /t:oabfldcheck /l /v:2)
Test 8-1: Checks to see if the following registry value is present. If it is, you will be given the option to remove this key: HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Exchange\\Exchange Provider registry key.
Test 8-2: Checks to see if the following registry value is present. If it is, you will be given the option to remove this key: HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Exchange\\Exchange Provider registry key.
NOTE: With this key present, the OABGen process can fail and this is not a recommended configuration.
Test 8-3: Checks to see if the following registry keys and values are present.
Exchange 2003 SP2 OAB Generation Registry Keys
HKLM\\SYSTEM\\CurrentControlSet\\Services\\MSExchangeSA\\Parameters registry key.
Checks for OAL NT5 DN Rejection registry value.
DS Access Keys
HKLM\\SYSTEM\\CurrentControlSet\\Services\\MSExchangeDSAccess\\Profiles\\Default registry key.
Checks for LDAPConnections registry value.
Checks for AsyncLDAPConnections registry value.
HKLM\\SYSTEM\\CurrentControlSet\\Services\\MSExchangeDSAccess\\Profiles\\Default\\UserDC1 registry key.
Checks for Hostname registry value.
Checks for PortNumber registry value.
Checks for IsGC registry value.
Checks for Hostname registry value.
Checks for PortNumber registry value.
Checks for IsGC registry value.
Test 8-4: Checks Windows Messaging Subsystem for user and Exchange Server MAPI profiles.
Test 8-5: Creates an OABInteg-Admin profile, which is deleted when OABINTEG completes successfully.
Test 8-6: Calls MAPILogonEx to obtain a MAPI Session.
Test 8-7: Select a profile and logon using our session.
Test 8-8: Checks the Sort Locale on the local machine.
Test 8-9: Checks the Code Page on the local machine.
Test 8-10: Call QueryIdentity and get the following information:
Profile linked to Mailbox:
Test 8-11: Call OpenAddressBook and Open the MAPI integrated address book.
Test 8-12: Checks to see if we can pull the server that we are trying to connect to for NSPI queries.
Test 8-13: Reads the Information Store table.
Test 8-14: Checks the Hierarchy Server and determines if the information store is online or offline.
Test 8-15: Grabs the PR_ADDRBOOK_FOR_LOCAL_SITE_ENTRYID attribute for the OAB system folders.
Test 8-16: Opens the OAB system folder inside the public information store using the value specified by PR_ADDRBOOK_FOR_LOCAL_SITE_ENTRYID.
Test 8-17: Search this folder’s hierarchy table for subfolders. Typically, these would be “OAB Version 2”, “OAB Version 3a” and “OAB Version 4”.
Test 8-18: Open the first folder that meets the above criteria. Also displays the following properties for the folder:
Test 8-19: Displays the following properties for each message in the folder:
Test 8-20: List the following properties for every attachment in each message:
Test 8-21: Display the following counters:
Message Class Normal found:
Message Class Differential found:
Message Class Unknown found:
Message Attachments found:
Messages found but unable to read the properties:
System folders found:
Highest sequence number found:
Lowest sequence number found:
Biggest attachment found:
Smallest attachment found:
Biggest message found:
Smallest message found:
Test 8-22: Delete the OABInteg-Admin profile.
Test 8-23: Log off the profile.
Test 8-24: Close the MAPI Session.
Test 8-25: Un-initialize MAPI Subsystem.
Test 8-26: Terminate the application.
TEST – [alltests] – Runs all the LDAP tests
This test will run all of the following tests in succession: [storealtest][altest][oaltest][abrtest][proxytest][rdntest][templatetest].
offlineABContainers – A multivalued distinguished name attribute that stores a list of distinguished names of address lists that should be included in this Offline Address Book.
offlineABServer – A single-valued distinguished name attribute that stores the distinguished name of the server that is responsible for generating this Offline Address Book. The server must be an Exchange 2000 Server.
doOABVersion – A single-valued integer attribute that stores compatibility information of this specific address book with different versions of Exchange. This attribute can be set to either “0” or “1”. (Any other value is reserved for future use.) A value of 0 indicates that this address book is not required to be compatible with versions 4.0 and 5.0 of Exchange. A value of 1 indicates that this address book should be compatible with versions 4.0 and 5.0 of Exchange in addition to Exchange 5.5 and 2000.
msExchOABFolder – A single-valued octet string attribute that is always set to a variant array with one element that stores a zero-byte array. Its existence is solely due to legacy systems.
offlineABSchedule – A single-valued octet string attribute that is set to a byte array of size 84 that stores the Offline Address Book update interval schedule. Each bit in this structure represents a 15-minute increment, starting from 12 AM Sunday. Each byte in this structure represents a 2-hour increment. Set the bit to “1” to schedule to run at the 15-minute interval.
offlineABStyle – A single-valued integer attribute that indicates more general exchange schedule information as follows:
0 = Never run. This is the same as setting each byte in the schedule blob in offlineABSchedule attribute to “0x00”.
1 = Run as specified by the schedule blob stored in the offlineABSchedule attribute.
2 = Run always. This is the same as setting each byte in the schedule blob in offlineABSchedule attribute to “0xFF”.
legacyExchangeDN – A single-valued distinguished name attribute that stores the legacyExchangeDN of the Exchange Organization to which this address list belongs. Exchange System Manager creates it as “<legacy domain name of the organization>/cn=addrlists/cn=oabs/cn=<legacy container name for the oab>”.
msExchOABDefault – A single-valued Boolean attribute that stores a value of either “True” or “False”. If set to True, it indicates that this is the default Offline Address Book for any mailbox store if not explicitly specified for that store. Only one Offline Address Book should have this value set to True.
systemFlags – A single-valued integer attribute that stores system information regarding the directory object. Although this is an optional attribute, it must be set at creation time as well. This attribute is set by passing a value that is defined by the ADS_SYSTEMFLAG_ENUM enumeration, which is documented at:
siteFolderGUID – A single-valued octet string attribute that is set to a random unique globally unique identifier (GUID) value for the Offline Address Book.
siteFolderServer – A single-valued distinguished name attribute that stores the distinguished name of the public folder store where you want the Offline Address Book to exist. The public folder store should be on the same server as offLineABServer to avoid network traffic.
msExchPurportedSearcyUIArray – A multi-valued attribute that stores the parameters necessary to rebuild the Exchange System Manager’s Offline Address Book query filter dialog for this Offline Address Book. This attribute does not have to be set. If it does not have a value set, then the Modify button on the Offline Address Book’s properties, when viewed through Exchange System Manager (ESM), would be disabled. Modifying this attribute is not supported and there is no documentation on how to customize this property. The best way to customize it programmatically is to create an OAB using a similar query filter from Exchange System Manager and copying the values of this attribute and pasting them into your code to make a new OAB that you are creating programmatically.
More Information on the OABGen Process
Microsoft Exchange System Attendant is responsible for generating the OAB using the oabgen.dll. This is a MAPI application (aka OABGen) that reads from Active Directory. The first time an OAB is created; OABGen creates the OAB Version 2 and OAB Version 3a folders. Every time OABGen runs, it performs several tasks:
- Creates the files for all OAB versions.
- Compresses the files.
- Creates posts in the system folders for each version of the OAB that it is configured to generate. The OAB files will be saved as attachments on the posts in the folders.
- Creates incremental OAB files containing daily changes. The default setting in Exchange Server 2003 is to generate an OAB incremental file every morning at 05:00.
Microsoft Exchange Information Store is responsible for storing the OAB system folders listed directly under the OFFLINE ADDRESS BOOK. Each time a new OAB is created, the corresponding OAB system folders are created, including the containers, such as EX:/o=<Organization Name>/ou=<Administrative Group>, and /o=<OrganizationName>/cn=addrlists/cn=oabs/cn=<name of Offline Address List> during nightly online maintenance.
Directory servers – Active Directory servers are utilized in OAB generation. OAB configuration data is stored in the Configuration Naming Context partition in Active Directory, making it available to all domain controllers. In addition, global address list information is stored in global catalog servers.
Recipient Update Service – Although OAB generation does not require the RUS, address lists do require this component. The System Attendant calls the RUS, which in turn maintains the address list membership on recipients. If the address list is blank, OAB generation will fail.
For some organizations, the OAB is a small file that remote users occasionally download. For these organizations, downloading the OAB is not a concern. However, for some large organizations that have large directories, or for organizations that have deployed Microsoft Office Outlook 2003 in Cached Exchange Mode, it may be a concern, especially if the organizations have consolidated Exchange servers into a regional datacenter.
OAB sizes can vary from a few megabytes to a few hundred megabytes. The following factors can affect the size of the OAB:
- The usage of certificates in a company. The more public key infrastructure (PKI) certificates, the larger the OAB. PKI certificates range from 1 kilobyte (KB) to 3 KB. They are the single largest contributor to the OAB size.
- The number of mail recipients in Active Directory.
- The number of distribution groups in Active Directory.
- The information that a company adds to Active Directory for each mailbox-enabled or mail-enabled object. For example, some organizations populate the address properties on each user; others do not.
For information about the address attributes stored by default in the OAB, see the following Microsoft Knowledge Base article:
“User Attributes Stored in Offline Address Book Files” in Working with the Exchange Server 2003 Store http://go.microsoft.com/fwlink/?LinkId=33049
For estimation purposes, the full OAB size is approximately 1 MB per 1,000 users. If there are user certificates in the OAB, this will add approximately from 1 to 3 KB per certificate. The size of the OAB and the available network bandwidth directly relate to the time it will take for all Outlook clients to download the OAB.
The readme contains much of the information above and is good for reference. In addition, the following Knowledge Base articles have great information about related topics:
249256, “HOW TO: Troubleshoot Intra-Site Replication Failures” http://support.microsoft.com/Default.aspx?kbid=249256
272314, “XADM: Preparing a Mixed Mode Organization for Conversion to Native Mode” http://support.microsoft.com/Default.aspx?kbid=272314
273364, “XADM: Unable to Create or Rebuild Default Offline Address List” http://support.microsoft.com/Default.aspx?kbid=273364
275171, “XADM: How to Reset System Folders on an Exchange 2000 Server” http://support.microsoft.com/Default.aspx?kbid=275171
286328, “Offline Address Book Is Missing and Cannot Be Generated in Microsoft Exchange” http://support.microsoft.com/Default.aspx?kbid=286328
307917, “XADM: How to Remove the First Exchange 2000 Server Computer from the Site” http://support.microsoft.com/Default.aspx?kbid=307917
311472, “XADM: Troubleshooting the Exchange 2000 Offline Address List” http://support.microsoft.com/Default.aspx?kbid=311742
321708, “HOW TO: Use the Network Diagnostics Tool (Netdiag.exe) in Windows 2000” http://support.microsoft.com/Default.aspx?kbid=321708
36074, “Enabling a
817377, “Offline Address Book Replication Does Not Work After You Upgrade to Exchange Server 2003”
822931, “How to Remove the First Exchange 2003 Server Computer from the Site” http://support.microsoft.com/Default.aspx?kbid=822931
823580, “How to configure how the Offline Address Book is downloaded when you use Outlook 2003 in Cached Exchange Mode”
839826, “High network usage occurs while Outlook clients download the offline Address Book from Exchange 2003 at the same time”
841273, “Administering the Offline Address Book in Outlook 2003” –http://support.microsoft.com/Default.aspx?kbid=841273
867623, “Throttling full offline Address Book downloads to limit the effect on a LAN in Exchange Server 2003”
820838, “OL2000: E-mail Messages That You Created While Offline Are Sent to the Wrong Recipient” http://support.microsoft.com/Default.aspx?kbid=820838
232767, “OL2000: Integrity Check For Client OAB”