Comcast and Postfix

sirsky sirsky at
Sun Feb 24 10:40:53 CST 2008

On Sun, Feb 24, 2008 at 9:51 AM, <ckeeter at> wrote:

> Hi all,
> I've been a long time lurker and need a shove in the right direction.
> I've been getting my email on Ubuntu box for a while, Fetch gets the mail
> and postfix sends it out, Recently Comcast has been forcing me to use the
> 587 port for sending mail. and I'm at a loss on how to get it to work in
> postfix. I can't even send mail to a 3rd part mailhost, so they have locked
> me out of port 25.
> Has anyone else had this problem and solved it and can point me in the
> correct direction, this has been driving me crazy.
> Thanks!!
> Chuck Keeter
> _______________________________________________
> Kclug mailing list
> Kclug at


With any *normal* ISP (Time Warner) the process would be:

Edit your /etc/postfix/ file.  Find the relayhost directive.  Set
that to your ISP's outgoing SMTP server.  Postfix will then send all
outgoing mail through your ISP, instead of trying to deliver it directly.

However, since Comcast is far from a *normal* ISP...

1. You will need to have Postfix send out on port 587.  Edit

     relayhost = []:587

2. You will need to use SMTP Authentication to authenticate with Comcast's
SMTP server.

Hope this helps.


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