SMTP server or "forwarding"?

[Roger Grosswiler]

> Jonathan Berry wrote:
>> On 8/27/05, Craig White <craigwhite at azapple.com> wrote:
>>
>>>On Sat, 2005-08-27 at 00:11 -0500, Jonathan Berry wrote:
>>>
>>>>Hey everyone,
>>>>
>>>>Okay, a lot of ISPs now block port 25 out to anything other than their
>>>>SMTP server.  In some situations, it would be nice to circumvent this
>>>>to get to another SMTP server if one is not available.  So what I had
>>>>though is to setup my FC4 linux box to listen for SMTP traffic on a
>>>>non-standard port.  Actually, I could just have my hardware router
>>>>forward whatever port to 25 on the computer, so the non-standard port
>>>>part should be easy.  It would be nice to have a workable solution
>>>>with as little as possible.  Does anyone know of some way that I could
>>>>maybe take any traffic to my server on my chosen high port and forward
>>>>it along to my ISP's SMTP server on port 25?  It sounds possible, but
>>>>sketchy enough to where it might not be.  Any ideas?  I figure I could
>>>>always just setup my own SMTP server and that should work.  But I
>>>>would need to make sure I did that right as I do not want to aid in
>>>>the spread of spam and/or viruses.  Since it would be on a strange
>>>>port, it shouldn't be as big a problem, if at all.  Any ideas on that
>>>>point?  So, what do you think of my idea and options?  If I were to go
>>>>the route of setting up my own SMTP server (perhaps even so far as a
>>>>whole email server) any tips as to where to start looking for info on
>>>>doing this right?
>>>
>>>----
>>>There's often no reason to do what you are speaking of.
>>>
>>>You can set Postfix or Sendmail to use your ISP's smtp server as a
>>>'smart host' so outbound email will be delivered. Then other computers
>>>can use the system running Postfix or Sendmail delivering via the smart
>>>host can send mail. The only issue is computers that aren't on your
>>>local lan can't use your mail server to relay mail - which stands to
>>>reason.
>>>
>>>If for some reason you really believe you need to do what you are
>>>asking, the following is offered in sendmail.mc (and I presume something
>>>similar is configurable for postfix)
>>>
>>
>> [snip]
>>
>>>dnl DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl
>>>
>>>and at this point - the ISP's blocking ports 25, 80, 137-139, 445 are
>>>not blocking 587
>>>
>>>Craig
>>
>>
>> Okay, well I guess I should stop trying to be general and explain the
>> situation.  My sister is away at college right now and she has to
>> connect to the internet through the university's network.  Of course,
>> they block port 25 out to our (home) ISP's SMTP from their network.
>> The university supplies students with email, but this has to be
>> accessed via a web interface.  They provide IMAP connectivity for
>> professors, but not students (who knows the reasoning for some
>> university policies?).  So to my knowledge, there is no SMTP server
>> that she could use to send email with a normal client (she uses
>> Windows by the way).  So, what I want is to setup something to where
>> should could send email to my Linux server, which would then send it
>> out to my ISP's SMTP server to go wherever it needs to go.  But since
>> port 25 out is blocked, my server needs to listen on a different port.
>>  I was just going to pick some random, high number like 4539 for
>> instance.  So this is the desired path:
>> Computer on non-standard port
>> University LAN
>> Internet
>> My Public IP
>> My Local LAN
>> Linux Server
>> ISP's SMTP
>> Continue just like I was connecting directly to the SMTP server
>>
>> Does that make sense now why I want this?  Is something like this
>> possible?
>
> Yes, and the "standard" approach for this is to provide an SMTP
> submission service on your Linux server (port 587). Your sister
> authenticates to your server using SMTP AUTH, submits her mail just like
> she would with a regular SMTP server and then your server gets on with
> the job of delivering it.
>
> If you're using sendmail, search for "MSA" in /etc/mail/sendmail.mc
>
> You'll need to set up SMTP AUTH for yourself, but google is your friend
> there.
>
> Paul.
>
>
> --
> fedora-list mailing list
> fedora-list at redhat.com
> To unsubscribe: http://www.redhat.com/mailman/listinfo/fedora-list
>


i know, this is a very pragramatic approach. but why not installing a
webinterface like shipped-with squirrelmail on/for your mailserver? your
sister surely could also send mail and receive it by this webinterface.

Roger