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Roalt
Asked: 2010-12-30 01:26:19 +0800 CST

SMTP redirecting to other port than 25

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How can you redirect your smtp traffic to another port than 25? My ISP blocks incoming traffic to port 25.

I've been using ZoneEdit.com for this purpose for years (incoming mail traffic goes to another port and I redirect it via my firewall internally to port 25), but with the new system I cannot do it anymore.

I'm not sure if I can do this by configuring MX and A records in the right way or if I need a SMTP redirecting service (such as rollernet.us)?

I'm not an expert in Zone records but generally I know my way around for website traffic.

domain-name-system smtp domain-name zoneedit

3 Answers

  1. Best Answer

    There is no way to tell a sending server what port you're listening on using MX (or other records). You will have to use a reflector service. No-ip have a reflector service that will forward mail to a non standard port.

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  2. Above 2 answer all had some drawbacks, so this is what I did:

    1. I created a free account at rollernet.us
    2. I created a separate domain (yes DOMAIN NAME!) to receive my email (say mailaccount.com)
    3. I setup rollernet.us to create a SMTP Redirection to port xxxx of my own server for this mailaccount.com
    4. I configured the MX mail servers for the domain mailaccount.com (in my case at zonedit.com) to let them be handled by Rollernet's. (mail.rollernet.us and mail2.rollernet.us)
    5. For all accounts where I receive e-mail, I set-up an E-mail forwarding to my gmail account (say [email protected]).
    6. I set-up a forwarding e-mail from gmail to [email protected]
    7. I made sure my postfix on my personal servers handling incoming traffic.

    It's a bit complex (before I only needed zonedit to forward it my my higher than 25 port number), but it works. Other drawback is that I sacrify one domain name to handle my emails.

    • 0

  3. What email server are you using?

    If your ISP is blocking it on 25, you can specify another PORT to be used in your MAIL Server config. In Exchange 2007 you would change it in the Receive and Send Connectors via EMC or powershell. http://www.exchangelog.info/2007/08/how-to-change-smtp-port-25-in-exchange.html

    I think in Linux based email servers you may have to edit the config file and change the port.

    You would then open that port on your firewall and redirect it to your internal IP Address of your Mail Server.

    Hope that Helps

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