I am setting up a backup SMTP server which is located outside of our offices.
The idea is that it should accept all messages addressed to our domains (DNS metric is high, so this should happen only when internal smtp servers are down), and forward them to our internal smtp servers, when they are back up (in reality, it will try to do so every few hours).
I have created a transport map
example.com smtp:[ip of smtp server]:25 example2.com smtp:[ip of smtp server]:25
and I have set main.cf
transport_maps=/etc/postfix/transport default_transport:discard:Outgoing email disabled on this node relayhost= relay_domains =
The problem is that, when connecting via telnet, postfix still accepts messages addressed to any domain
When connecting via thunderbird, postfix works properly.
I'm not sure how to interpret this.