How to get warning email if email is delayed and deferred

How to get warning e-mail if e-mail is delayed and deferred?

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Problem

How to get warning e-mail if e-mail is delayed and deferred

Solution

We need to configure "zimbraMtaDelayWarningTime" attribute to achieve this.

For example, want to get the warning email in exact five minutes if the e-mail is deferred, then following is the command need to execute on MTA server:

 # su - zimbra
 $ zmprov ms `zmhostname` zimbraMtaDelayWarningTime 5m

Restart the MTA service:

 $ zmmtactl restart

If the warning message needed after 4 hours, then specify "4h".

Example of warning message:

-----------------------------------------------------------------------------------------------------------------------    
This is the mail system at host mail.domain.com.
####################################################################
# THIS IS A WARNING ONLY.  YOU DO NOT NEED TO RESEND YOUR MESSAGE. #
####################################################################

Your message could not be delivered for more than 0 hour(s).
It will be retried until it is 5 day(s) old.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
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Note: After implementing this notification, please be aware that it could potentially lead to an increased load on the MTA server as it attempts to send emails every 5 minutes. This could become problematic if there's a surge in spamming activity, as the MTA server might struggle to manage the high load, potentially affecting its ability to send and receive emails. Therefore, it's important to exercise caution when utilizing the mentioned attribute, considering the associated risks and potential impact on server performance.