Incorrect and expired E-mail addresses create the most annoying problems for mailing list administrators. The CommuniGate Pro LIST module automates processing of incorrect, expired, and temporarily unavailable addresses.
All messages sent to subscribers (in all modes) have message envelope information that routes all error reports back to the LIST module. When a report is received, the LIST module:
Most of the problems can be detected immediately when sending a list message from the CommuniGate Pro Server, so most of the error reports are generated locally, on the same CommuniGate Pro server. The CommuniGate Pro server generates reports in the proper format, so most of the delivery problems are handled automatically.
If a list message has been sent to a remote site without a problem, but then that remote site fails to deliver the message to the recipient, the delivery report is generated on that remote site. Most of the modern mail servers generate delivery reports in the correct format, so in this case many problems are handled automatically, too.
And, finally, it is still possible to receive unformatted delivery reports from other sites. The LIST module can store those unformatted reports in the listname/reports Mailbox, so the list owner can process them manually.
Each record in the delivery report contains information about one E-mail address, and indicates if the original message was or was not delivered to that address. It can also specify if the delivery problem is fatal (as when account is removed from the system), or if it is a non-fatal, temporary problem (as when a remote site is down or when the account disk space quota is exceeded).
If a non-fatal report is received, the E-mail address in question is suspended, and no list messages are sent to that address, and all additional error reports about that address are ignored. When the LIST module performs periodic list clean-ups, it sends a warning message to all suspended addresses. The warning message notifies that user that some list messages have not been delivered to the user address, and it also asks the user to confirm subscription (by replying to the warning message).
There are two ways to specify the suspension period:
When a user confirms the subscription by replying to the warning message, the suspension period ends, and the bounce counter associated with the user E-mail address is cleared.