[lug] Sendmail

[Chip Atkinson]

Maybe I'm just missing the entire problem, but you are kind of required 
to use port 25.  That's the port that servers speaking smtp 
traditionally listen and speak on and trying to connect to someone else 
on port 2500 won't work unless the other end is configured to use 2500 
as well.  If that is the case, then you could probably talk them into 
relaying mail for you, since they are reconfiguring their sendmail to 
talk with you anyway.

Port 110 is for pop3, which is good for downloading, but that would be 
used by the desktop machines to download mail from a main server.

Can you not set the "Smart" relay host in sendmail.cf to be 
smtp.ix.netcom.com and restart sendmail?  Then all outgoing email is 
sent through netcom but should make it to the ultimate destination.

The main machine that you configure to use as a relay will then be the 
main one that the desktop users connect to via port 110.

If I am indeed missing something and you can get away with using port 
2500, you might wish to look into ip port forwarding.  There's a brief 
how to on it and it would save you from having to tear into the 
internals of sendmail.  "Merely" use the forwarding to forward 
connections to and from port 25 to port 2500.

Chip

Greg Horne wrote:

> I would like to use a different port (other than 25) to send mail on.  
> Since Netcom is blocking 25, i'll use 2500, or some random unassigned 
> port.  My question was this:  How do I set sendmail up to allow both 
> port 25, and 2500 to be used to send mail?
> 
> Greg
> 
> P.S.  I am considering this because Netcom was of no help on the phone.  
> They just said that they only allow their @ix.netcom.com mail to go 
> through their servers.  I would like to use a relay, but I don't think 
> that is going to happen.  This port thing is my alternative.
> 
>> From: Chip Atkinson <catkinson at circadence.com>
>> Reply-To: lug at lug.boulder.co.us
>> To: lug at lug.boulder.co.us
>> Subject: Re: [lug] Sendmail
>> Date: Fri, 14 Sep 2001 12:13:52 -0600
>> 
>> I'm not sure I entirely understand the problem, but it sounds like what
>> Qwest does too.  Basically you have to use their machines as relays for
>> outbound mail. Why is this a problem?  I run a moderately busy mailing
>> list and haven't had any problem with the relay part.  Originally I
>> wanted to do my own delivery to reduce their load, but since they want
>> it that way, I just said to myself "screw 'em".
>> 
>> Greg Horne wrote:
>> 
>>> Check this out!
>>> 
>>> So I go on a consulting job to a company to set them up with e-mail
>>> through my company.  There e-mail is @company.com, so smtp.company.com
>>> is what they would use for mail servers.  Port 25 for sending and port
>>> 110 for receiving.  I set everybody up, and checking mail was just
>>> fine.  When I went to send a test mail they got the error 10,060, which
>>> when I looked it up meant that their ISP (Netcom) is blocking all
>>> outgoing port 25 communication unless is goes through their mail servers
>>> first (smtp.ix.netcom.com).  I sent an e-mail to netcom and am waiting
>>> for a response.  I also looked around the net and found that to get
>>> around this people are using alternate ports for sending like 2500.  My
>>> question is this:  How can I set up sendmail to use port 25 for e-mail,
>>> but also use a new port 2500 for the mail @company.com?  Can these two
>>> ports work in tandem or would I have to move all clients to 2500?
>>> 
>>> Thanks,
>>> Greg Horne
>>> 
>>> P.S.  A lot Netcom does this blocking of port 25 to other smtp servers
>>> to prevent their users from spamming.  When a coworker of mine talked to
>>> them on the phone they said it was in the terms of use.  Bleh!
>>> 
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