[NCLUG] comcast blocking port 25?

[Bob Proulx]

This may be of benefit to others in the area now needing to update
their configuration to relay mail through comcast.  My friend says
this (but I don't know who wrote the original instructions and so
can't attribute them properly) "I followed these instructions and it
worked perfectly, of course with the correct smtp server name."  I
made a few tweaks to the instructions.  I am not using Comcast myself
and can't test this but I will forward these along with the hope that
they will be useful to others.

Debian Postfix centric instructions.

* sudo apt-get install postfix-tls libsasl2-modules
* Add the following settings to /etc/postfix/main.cf:

  smtp_sasl_auth_enable = yes
  smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
  # Line below permits plaintext across the wire...
  smtp_sasl_security_options =
  # Replace the following with your designated mail relay.
  relayhost = mail.example.com
  transport_maps = hash:/etc/postfix/transport

* Create /etc/postfix/sasl_passwd as follows:

  mail.example.com  username:password

* Route outgoing mail through the mail relay on port 587 by adding
  this line to the end of the /etc/postfix/transport map file.  The
  star '*' here is a literal star wildcard to match everything.

  *  smtp:[mail.example.com]:587

* sudo chown root:root /etc/postfix/sasl_passwd
* sudo postmap hash:/etc/postfix/sasl_passwd
* sudo postmap hash:/etc/postfix/transport
* sudo chmod 600 /etc/postfix/sasl_passwd*
* sudo /etc/init.d/postfix reload

According to the postfix docs here the transport configuration above
should be available directly in the 'relayhost' setting.

  http://www.postfix.org/postconf.5.html#relayhost

Which would mean something like this.  But again, this is deduced
academically from the docs and I have not tested it.

  relayhost = [mail.example.com]:587

Hope that helps someone.

Bob