I am running a Zimbra mail server version 7.2.7 on a Linux CentOS server. My email address is xxx@azucarcolombia.com.
When I send email to yyy@prosalon.com.co, the email immediately bounces, and the bounce email says:
The mail system
<yyy@prosalon.com.co>: host mail.prosalon.com.co[174.37.44.242] said:
501 5.7.1 <xxx@azucarcolombia.com>... Sender IP must resolve (in reply
to RCPT TO command)
I have tried to change the zimbra smtp banner with the following command on the zimbra CLI, but the problem persists:
zmprov mcf zimbraMtaMyHostname correo.azucarcolombia.com
To be clear, this only happens when sending to some specific email addresses. Gmail, for example, works fine.