On Thu, Dec 15, 2016 at 02:23:02PM -0600, Ramon F Herrera wrote:
> I have 2 rented servers: one running sendmail (for a while, works fine) and
> the other running Postfix (going through the learning curve)/./
Two servers, potentially two firewall policies.
> My VPS provider (1and1.com) gives me the ability to control my *inbound*
> firewall. However, the problem is that a command like this is blocked:
>
> % telnet any-host-other-than-localhost 25
>
> Somehow, sendmail is able to bypass that limitation (out of the box, no
> special configuration), but Postfix cannot. The messages stay in the queue
> and eventually bounce.
Sendmail is not bypassing firewall rules. Either the rules for
the Sendmail machine are different, or it is not sending to
"any-host-other-than-localhost". If Sendmail is delivering outbound
email, then either the rules are different, or it is relayign all
email via a "smarthost", and connections to that are not blocked.
The smarthost could be 1and1's relay MTA on port 25, or some MSA
on port 587, for which you have SASL login credentials.
You need to look in your Sendmail logs and configuration to determine
how outbound mail is processed.
--
Viktor.
