Mail Protection: Configurable SMTP proxy port
Allow the SMTP proxy to be configured to run on a port other than 25, for users with ISP blocks on port 25 traffic.
MarCow
shared this idea
8 comments
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Dmitry Nesterkin
commented
Very necessary functionality! It is possible to configure DNAT to make it listen on any port, but there is no way to block port 25 from internal interfaces (protection against bots, malware etc)
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FYI, The SMTP proxy already listens on other ports than port 25. You can use port 587 for authenticated SMTP (RFC 4409) and port 465 with TLS on connect.
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SPS
commented
DNAT & SNAT - does not fit. SMTP Relay must accept SMTP-traffic on any port, and do forward to any port. Too many Mail Server for SMTP work with other ports, including Clients are configured on different ports for the protection of BOTs Adware.
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SPS
commented
a very necessary function
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Bob Alfson
commented
Martin, this functionality already is possible with DNAT and SNAT rules.
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Jason Hamilton commented
ok and I was wrong it's now 20 bucks a year for the dnsexit service.
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The problem with this is trying to tell the external smtp servers to redirect the smtp traffic to a different port. When I had a e-mail server running at home I used a service by dnsexit http://www.dnsexit.com/Direct.sv?cmd=mailRedirect to do this for me so that way everything was still using port 25 on the outside and just relaying through their servers it only cost like 10 bucks a year to do it. The other thing you could try is google apps for your domain they will allow you to have 100 e-mail boxes for free. That was what I ultimately switched my email to so that way I wasn't violating my TOS with my ISP otherwise you might have to get business class service from your ISP.
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Bob Alfson
commented
My home has a Linksys router. Linksys calls it "Port triggering" when you change 26 to 25. I assume that that would work if the device were in bridge instead of router mode.
