Hi,

I’m setting up a Mail Server on AWS with MailCow. I have decided to use port 2525 as my SMTP PORT, but so far I’m getting this Error: “454 4.7.0 TLS not available due to local problem” when I attempt to STARTTLS.

I also get this on my mail admin postfix logs, “ Relay access denied (in reply to RCPT TO command))”

Can anybody assist with this?

  • esackbauer replied to this.

  • I don’t know why you would want to use a custom port. TCP/25 is standard for SMTP, and also needed if you want to send or receive email from/to other mailservers.

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    I don’t know why you would want to use a custom port. TCP/25 is standard for SMTP, and also needed if you want to send or receive email from/to other mailservers.

    esackbauer I assumed AWS blocks port 25

    [unknown] I assumed AWS blocks port 25.

    [unknown] I assumed AWS blocks port 25.

      • pkernstock

        • Forum Staff
        • volunteer
        Moolevel 57
      • Post #5

      They do by default, yes. And changing the ports to anything except TCP/25 will render your mailserver not able to receive/send emails to/from other mailservers.

        pkernstock So, I have no recourse but to ask for permission?

        pkernstock Chat GPT said I can use a relay port, like 587 to send the mail. In the postfix form of [mail.server.com]:587 as the value for relayhost.

            • pkernstock

              • Forum Staff
              • volunteer
              Moolevel 57
            • Post #7

            Yes, you - as the client - can. But ideally you also want your mailserver to deliver emails to other mailservers - and TCP/25 is used for this.

            Thanks a lot. I’ll try get the block removed or buy a VM that doesn’t block port 25.

            Thanks. Got a VPS from DartNode.

            pkernstock is it possible to forward smpt trafic to a vps on port 2525 and from the vps sending it with port 25?

                • esackbauer

                  • Community Hero
                  Moolevel 379
                • Post #10
                • Edited

                knaftoli Yes thats possible. This is named “sender dependent transport” in mailcow where you configure the relay server and assign this sender dependent transport to the domains that should use it.

                  • Mmlcwuser

                      Moolevel 36
                    • Post #11
                    • Edited

                    knaftoli Yes but that makes the hole setup more complicated. Why not just run Mailcow on that VPS then?

                    Sure, you’ll probably need a more powerful VPS than if you were just using it as a proxy, but overall it doesn’t have to be more expensive. I mean, it’s not like AWS is giving away their compute resources for free, is it? ;-)

                        mlcwuser I used DartNode, I purchased a VPS with 2 vCore $7, they’re having a valentine’s special.

                        Here’s the Link:

                        https://dartnode.com

                        My Server is now Running, with Port 25 open, Sending and Receiving Mails.

                        (EDIT @pkernstock: Removed affiliate link.)

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