Google Message Security Troubleshooting Guide - Manual (Page 61)

Mail Flow Troubleshooting 63
Why am I not getting mail from one sender?
Follow these steps to find out why you can’t receive mail from a single sender.
Common Causes
If a single sender is unable to send you mail, here are some common causes:
• Sender mail server: The problem may be happening on the sender’s side,
either due to mail server issues, network issues, or DNS issues.
• Connection Manager blocking: Sometimes the message identifies a sender
as the source of an email attack and blocks mail. You can set up a pass-
through to prevent this from happening.
• Filter Settings: You may have a filter set up to block mail from the sender. You
can usually identify what’s causing this by looking at the error message.
• Recipient mail server: Your own server may be rejecting the message. The
message security service passes any errors generated by your server back to
the sending server, so you can usually identify what’s happening by looking at
the error message.
First Steps of Troubleshooting
Begin troubleshooting by collecting information about what’s happening.
1. Confirm that the problem is only happening for one sender. Send a test
message to your mail server from an outside mail account such as your
personal Gmail account. If the problem is happening for multiple senders, see
“Why am I not getting any mail at all?” on page 57 for troubleshooting steps.
2. Contact the sender directly and collect the following information
• The error message the sender gets when trying to send mail.
• The IP address of the sending server.
3. If the sender doesn’t know their IP address, you can collect this information
through other emails.
• If the sender has sent messages successfully in the past, look at an old
message from the sender and review the full headers for the IP
information.
• Otherwise, ask the sender to send mail to a third-party email address,
such as your personal Gmail account. Look at the headers to get the
sending server’s IP address. To see the full headers in Gmail, click the
blue triangle on the upper right of the message and select “Show Original”
from the pull-down menu.