A new SMTP related issue has been brought to our notice and we are currently working on fixing it. This post provides information about an issue under investigation and is subject to change.
When you make changes to the properties of a SMTP Virtual Server under the Access tab you get the following message :
SMTP Configuration - Unspecified Error
The problem is likely to occur when you have the HOTFIX 946517 on the server. The HOTFIX 946517 updates the Adsiis.dll to fix a thread contention issue seen when you run MOSS 2007 Timer Service.
Currently if you are running SMTP on a server with MOSS 2007 you will have to uninstall the HOTFIX 946517 to get your SMTP working. Note that the SMTP service it self is not affected by this HOTFIX and keeps running. But you cannot make changes like Relay restrictions. A fix for this problem will be made available shortly in the form of a HOTFIX and published as KB 950426