I'm having an intermittent problem sending mail out from the zimbra box. When I send an email to a domain, say, firstname.lastname@example.org (my work account), I get a bounce back:
This is the Postfix program at host zimbra.mapolce.com.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
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.
The Postfix program
<email@example.com>: host mapolce.com[18.104.22.168] said: 553 sorry, that
domain isn't in my list of allowed rcpthosts (#5.7.1) (in reply to RCPT TO
But that IP address for mapolce.com is the A record for mapolce.com, not the MX record.
Why is it looking up the A records for the domains rather than the MX?