Getting Postfix to Send Mail From a Comcast Network

Since I moved to Comcast a while back, I have not received emails from this blog server telling me that comments have been left. This is a drag because spam comments can pile up for a while before I think to go looking for them and delete them. So today I took the time to figure out how to get Postfix to send mail through the Comcast server. Kudos to Kclug mail list post by “Lucas,” which explains the issue in very simple terms. The key is to tell Postfix to relay mail through the Comcast mail server on port 587 (which is the correct port for Comcast to use for their users to send mail) and to use your Comcast.net username and password to connect. So I put this in my main.cf:

relayhost = [smtp.comcast.net]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/passwd
smtp_sasl_security_options =

Then, following the instructions in this Freelock Knowledge Base article, I put this in my passwd file:

smtp.comcast.net    myusername:some_password

I actually had to contact Comcast to get my username and password, since I had never used the Comast mail server or other services before. But they gave it to me without problem. Then I just ran this and was good to go:

chown root:root /etc/postfix/sasl/passwd;
chmod 600 /etc/postfix/sasl/passwd
postmap /etc/postfix/sasl/passwd 
postfix reload

And now maybe someone else will stumble upon this blog entry when they're Googling for a solution and get the help they need, too. No doubt I'll be looking for it again in a year or so, the way things go.

Backtalk

weave wrote:

... or move your linux box outside of Comcast

I just got nailed with this, but my server is "on the outside" hosted on Linode. My security webcam could not email my host and had no option to use port 587, so I had to use iptables to rewrite the port to something else and change my postfix on that server to listen in on that port.

http://blog.weaverling.org/2009/03/08/getting-around-comcast-port-25-block

Your way is def easier since it doesn't involved an outside server to relay the messages, of course. I'm just trying to avoid comcast handling any of my email. Just a wee bit paranoid -- especially since my webcam picks up some embarassing things once in a while (like me running around in my underwear -- gack!)

Anyway, I'm going to edit my blog post to point here for an alternative way of doing this. Thanks!

Theory wrote:

Re: ... or move your linux box outside of Comcast

weave—

Yeah, I just have system monitoring-type messages sent from that box, so I'm not concerned about them going through the Comcast mail server. My main mail server is hosted elsewhere. Good to know there are other hacks, though. Thanks!

—Theory