In case you are getting an error message when you try to send an email to a recipient whose email address is in Office 365? If you think you should not be receiving the error message, you can use the delist portal to remove yourself from the Office 365 blocked senders list.
Exchange Online Protection uses the blocked senders list to protect its customers from spam, spoofing, and phishing attacks. Your mail server's IP address, that is, the address your mail server uses to identify itself on the Internet, was tagged as a potential threat to Office 365 for one of a variety of reasons. When Office 365 adds the IP address to the list, it prevents all further communication between the IP address and any of our customers through our datacenters.
You will know you have been added to the list when you receive a response to a mail message that includes an error that looks something like this:
550 5.7.606-649 Access denied, banned sending IP [IP address]; To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to http://go.microsoft.com/fwlink/?LinkID=526653.
where IP address is the IP address of the computer on which the mail server runs.
Step 1: Enter a valid email address to receive a verification email to complete the check, and enter the public IP address of the messaging server you want to check.
To use the Office 365 delist portal to remove yourself from the blocked senders list
- In a web browser, go to https://sender.office.com.
- Follow the instructions on the page. Ensure that you use the email address to which the error message was sent, and the IP address that is specified in the error message. You can only enter one email address and one IP address per visit.
- Click Submit.
|Office 365 AntiSpam IP Delist Portal|
The portal sends an email to the email address that you supply. The email will look something like the following
|Click to confirm your email address|
Step 2: A new browser window will open to allow you to delist the IP address you entered in step 1. Click the Delist IP Address button.
|Step 2: Delist IP Address|
If the IP address is not on the blocked list, you'll see a message similar to the one below:
|Step 3: The IP address is not currently blocked by EOP|
If the IP address is blocked it will be submitted to be automatically delisted. The website says this takes about 30 minutes, but in practice I've seen it take up to 24 hours. You will not get a confirmation email when the IP address has been delisted. You'll need to re-run the test occasionally until you see that it's not blocked.
|Step 3: The IP address is blocked, but will be delisted|
After the IP address is removed from the blocked senders list, email messages from that IP address will be delivered to recipients who use Office 365. So, make sure you're confident that email sent from that IP address won't be abusive or malicious; otherwise, the IP address might be blocked again.
The quick geek way to test if your IP address is blocked is to use the telnet client. From the messaging server, telnet to the EOP endpoint using port 25 and try to send an SMTP email. You can find your EOP endpoint using www.mxtoolbox.com. If your IP address is on the EOP block list you will see it after the RCPT TO command . Here's an example of the telnet output:
Here, you can see that the IP address is banned by EOP and instructions for removal.
550 5.7.606 Access denied, banned sending IP [x.x.x.x]. To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to http://go.microsoft.com/fwlink/?LinkID=526655 (AS16012609)