Changing SendMail Port Number
Barbish3 at adelphia.net
Sun Jun 6 10:20:15 PDT 2004
Port 25 is the world wide internet standard for smtp mail servers to
listen on for inbound mail. There is no problem of changing your
smtp email server to listen on port 24, except for the fact that no
body on the internet can reach your smtp email server because they
will be sending to port 25 which your ISP has blocked and you are
not listening on. So for all practical purposes it does nothing for
Last year I read that zoneedit was developing an port 25 redirect as
an companion to their port 80 redirect.
Check out www.zoneedit.com to see if it's available yet. Besides
ISP blocking port 25, port 80 is also blocked for the same reasons.
Once you sign up for the free zoneedit service all your domain name
driven traffic passes through zoneedit. You can configure your
zoneedit account to redirect port 80 to say port 8080 and then
config your web server to listen on port 8080 and you bypass your
ISP's block. If zoneedit has it's port 25 redirect available it will
allow you to do same thing.
Check it out and the other free zoneedit like companies out there.
One of then may have port 25 redirect working. If you find any
please report back to this thread for the archives.
From: owner-freebsd-questions at freebsd.org
[mailto:owner-freebsd-questions at freebsd.org]On Behalf Of Doug Hardie
Sent: Sunday, June 06, 2004 12:29 PM
Cc: Gerard Seibert; freebsd-questions
Subject: Re: Changing SendMail Port Number
On Jun 5, 2004, at 17:35, Mark wrote:
> Gerard Seibert wrote:
>> This is probably a stupid question, but how do I change the SMTP
>> number that SendMail listens in on? I want to change it to
>> else, like perhaps 24. My ISP is blocking 25 and I want to get
>> that problem.
> And how will clients (the world) find you then, on port 24?
> Besides, are you sure your ISP blocks *incoming* port 25? That is
> unusual; *outgoing* 25, yes (for dialup users), but incoming?
> same difference: you can start sending on port 24, but since the
> listening on port 25, that will do you little good.
There are ISPs out there that block port 25 to any destination other
than their mail server. If you are connected to one of them there
no way to access your ISP's mail server. Thats why we provide
for both ports 25 and 26. I have never seen port 26 blocked.
all mail clients provide the ability to change the port it uses. We
provide instructions to our users on how to make that change if they
need it sl that they can send mail through our server. We do
the use of SMTP-AUTH to avoid an open relay. Blocking port 25 is an
attempt to prevent the use of open relays.
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