Moving an existing Mail Relay from one VM to another.

Andrews, Vincent v.andrews at
Wed Mar 17 08:48:27 UTC 2021


Our existing mail relay is in need OS change, we have created a new one based around CentOS 7 an MailScanner V5.3.4.

Everything seems to check out – ‘—lint’ passes without error.

Because the new system is not a legitimate mail relay – we cannot do any further testing until we move the IP address over.

We moved the IP Address from the existing VM to the new and changed /etc/hostname and rebooted.

Mail started to be accepted and was processed as we would expect – MailScanner was identifying Spam and passing everything as normal. The messages were passed to sendmail for processing.

We then noticed that mail was being delayed by two key 365 domains. We left it like that for about 40 minutes and then reverted to the existing server. After which mail was processed correctly. The messages in /var/spool/mqueue were moved to the existing system and within 10 minutes everything was cleared.

Has anyone had a similar experience?

Could it be that the new VM – having a different MAC address – was being flagged as an illegal mail relay?

Thank you for your help, and sorry about the essay.

Vincent Andrews.

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