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  3. Forward emails to remote SMTP server

Forward emails to remote SMTP server

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  • B Offline
    B Offline
    binary1zero
    wrote on last edited by
    #9

    Another question is that can I even use Cloudron as a "relay server" from downstream server ? I wasn't able to find any option to whitelist IP or any other way apart from authenticating users at cloudron for outbound emails.

    1 Reply Last reply
    0
    • infogulchI Offline
      infogulchI Offline
      infogulch
      wrote on last edited by
      #10

      Previous discussion on the topic:

      https://forum.cloudron.io/topic/6046/proxy-email-via-vps/9

      B 1 Reply Last reply
      2
      • infogulchI infogulch

        Previous discussion on the topic:

        https://forum.cloudron.io/topic/6046/proxy-email-via-vps/9

        B Offline
        B Offline
        binary1zero
        wrote on last edited by
        #11

        @infogulch Thank you that was insightful.

        Outbound is answered via that post.

        For inbound, here's what I'm thinking now :

        • Setup private wireguard connection between DO and my home server
        • Turn off Inbound email on DO Cloudron.
        • Redirect inbound ports like TCP/25 via iptables on DO to home server via wireguard
        mehdiM 1 Reply Last reply
        2
        • B binary1zero

          @infogulch Thank you that was insightful.

          Outbound is answered via that post.

          For inbound, here's what I'm thinking now :

          • Setup private wireguard connection between DO and my home server
          • Turn off Inbound email on DO Cloudron.
          • Redirect inbound ports like TCP/25 via iptables on DO to home server via wireguard
          mehdiM Offline
          mehdiM Offline
          mehdi
          App Dev
          wrote on last edited by
          #12

          @binary1zero From the constraints you mentioned, I do not understand why you don't simply use the home server as a main email server, but with an external relay for outgoing email (assuming your ISP does not block inbound 25).

          From what I know, PTR and stuff is only necessary for outbound relay, as it mostly affects server reputation when other server decide incoming email is spam.

          infogulchI girishG 2 Replies Last reply
          2
          • mehdiM mehdi

            @binary1zero From the constraints you mentioned, I do not understand why you don't simply use the home server as a main email server, but with an external relay for outgoing email (assuming your ISP does not block inbound 25).

            From what I know, PTR and stuff is only necessary for outbound relay, as it mostly affects server reputation when other server decide incoming email is spam.

            infogulchI Offline
            infogulchI Offline
            infogulch
            wrote on last edited by infogulch
            #13

            @mehdi iirc, one signal used to detect spam is whether the inbound and outbound IPs are the same. Maybe this is not the case, but Google and Microsoft are pretty finicky about email delivery so my instinct is to keep the externally visible configuration 'clean'. That's why I am looking at a design like this.

            girishG 1 Reply Last reply
            0
            • mehdiM mehdi

              @binary1zero From the constraints you mentioned, I do not understand why you don't simply use the home server as a main email server, but with an external relay for outgoing email (assuming your ISP does not block inbound 25).

              From what I know, PTR and stuff is only necessary for outbound relay, as it mostly affects server reputation when other server decide incoming email is spam.

              girishG Offline
              girishG Offline
              girish
              Staff
              wrote on last edited by
              #14

              @mehdi said in Forward emails to remote SMTP server:

              From what I know, PTR and stuff is only necessary for outbound relay

              that's correct. PTR is for the server that does the mail transfer, so it won't be needed if an external relay is used. On Cloudron, the PTR check is skipped when using a relay.

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              • infogulchI infogulch

                @mehdi iirc, one signal used to detect spam is whether the inbound and outbound IPs are the same. Maybe this is not the case, but Google and Microsoft are pretty finicky about email delivery so my instinct is to keep the externally visible configuration 'clean'. That's why I am looking at a design like this.

                girishG Offline
                girishG Offline
                girish
                Staff
                wrote on last edited by
                #15

                @infogulch inbound/outbound IP match is not needed. The reputation of outbound IP is very important though.

                If @binary1zero is using some business IP from their ISP, one can just host the mail server from home/office instead of all this forwarding.

                B 1 Reply Last reply
                3
                • girishG girish

                  @infogulch inbound/outbound IP match is not needed. The reputation of outbound IP is very important though.

                  If @binary1zero is using some business IP from their ISP, one can just host the mail server from home/office instead of all this forwarding.

                  B Offline
                  B Offline
                  binary1zero
                  wrote on last edited by
                  #16

                  @girish So I tried direct MX to my home and got errors:

                  [Default] 451-'4.7.1 Greylisting in action, please come back later' (delivery attempts: 5)>'
                  

                  So back to my original problem now - I'm thinking of either putting procmail on Synology and fetch emails or either use iptables/VPN route to send email home.

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                  • robiR Offline
                    robiR Offline
                    robi
                    wrote on last edited by
                    #17

                    I think you're looking for more of a mail relay setup with archival things done for incoming emails.

                    Conscious tech

                    1 Reply Last reply
                    0
                    • jamesJ Offline
                      jamesJ Offline
                      james
                      Staff
                      wrote last edited by
                      #18

                      Closed due to inactivity

                      1 Reply Last reply
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                      • jamesJ james has marked this topic as solved
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