Recipient Limit of a Message in Zimbra


We received some complaints from one of our customers regarding problem of sending email, especially rate limit, to Gmail. After some diagnosis, we found that the users keep 70-80 email addresses in TO/CC/BCC.

In order to restrict users to send emails on such accounts at a time, we implemented a policy. After executing this policy, users shall not be able to add more than 10 email addresses in a message.

root@mail:~# su – zimbra

Check the current limit:

zimbra@mail:~$ postconf | grep smtpd_recipient_limit 
smtpd_recipient_limit = 1000    ##This is the default recipient limit

zimbra@mail:~$ postconf -e 'smtpd_recipient_limit = 10' 

It will restrict the recipient limit to 10. You may adjust the number based on your scenario.

To apply settings.
zimbra@mail:~$ postfix reload

After applying this settings, you will get an error while sending a message greater than the threshold value (in this case: 10).



It is also to be mentioned that you can’t restrict to/cc/bcc field individually. Rather it will apply on all recipients of a message.

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