Not able to change the Submission port to 587

[Shamri04]

Hi Team,

I am using Postal with port 25 for both submission and delivery. Postal clearly states that port 587 cannot be used for delivery, which is fine. We are trying to change the submission port to 587 with STARTTLS enabled, so that when a client sends an email to Postal, the connection is encrypted.

I have tried multiple changes in the configuration file, but nothing has helped. I am still unable to see port 587 listening when checking with the netstat command.

[WantedFreak]

I redirect traffic with iptables like so

iptables -t nat -A PREROUTING -p tcp -m tcp --dport 587 -j REDIRECT --to-port 25
iptables -t nat -A OUTPUT -p tcp -m tcp --dport 587 -j REDIRECT --to-port 25

Now both port 25 and 587 works.

[willpower232]

that sounds about right but remember that Postal requires explicit STARTTLS so it may be that 587 does not work because the mail server you're using might expect it to be secure from the off

[thomasr007]

Hi Willpower,

How can we restrict non-encrypted SMTP communication from clients? Our requirement is that clients should be able to communicate with the Postal server only using STARTTLS over port 587 or port 25. Plain-text (unencrypted) connections should not be allowed.

Could you please help us with the required configuration?