Any receiver having auto-reply enabled will result in an auto-reply mail being sent back to the sender address for any notifications sent out from Zabbix. I.e. for no-reply addresses will end up bouncing with several retries and mails received as a consequence.

By including certain headers to the mails sent will make the receiver (server) skip sending auto-reply for these types of mails.

Patch for applying the headers has been attached to this issue.

Details of the related headers:

• http://www.redmine.org/issues/19558
• https://www.jitbit.com/maxblog/18-detecting-outlook-autoreplyout-of-office-emails-and-x-auto-response-suppress-header/