Moving an existing Mail Relay from one VM to another.

Andrews, Vincent v.andrews at
Tue Mar 23 08:19:13 UTC 2021

Thanks for your comments.

I have just successfully moved the system over to a new VM. It turned out that the issue was to do with Network Manager and how I had moved the ifcg file for the network port.

$ mv ifcfg-eno323232
$ mv as-Y- ifcfg-eno323232 ifcfg-eno323232
$ reboot

Network Manager attempted to load the new ifcfg but found a conflict with the renamed one. Even though it accepted the new IP address (from the retired system) and I could log on, sendmail was having none of it and failed to forward on mail that MailScanner had passed.

This error only produced a warning message in the messages file.


On 17/03/2021, 17:51, "MailScanner on behalf of Mark Sapiro" < at on behalf of mark at> wrote:

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    On 3/17/21 1:48 AM, Andrews, Vincent wrote:
    > We moved the IP Address from the existing VM to the new and changed
    > /etc/hostname and rebooted.
    > 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?

    There are always issues with new mail servers whose IP address has not
    yet developed a reputation, but IIUC, from the remote's point of view,
    the IP hasn't changed.

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

    And how would the remote SMTPD server determine the MAC of the sending
    server? I don't think that's possible. I don't know why there would be
    an issue if the IP didn't change. What is the content of the 4xx
    responses from the remote?

    Mark Sapiro <mark at>        The highway is for gamblers,
    San Francisco Bay Area, California    better use your sense - B. Dylan

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