Mail Server Relay Authentication Failure in Server Admin

Question

I need to set up Mail Server to relay through my ISP.  I know that I can authenticate to smtp.comcast.net:587 using my account and TLS usnig a mail client.
However, when I use Server Admin to configure my server's SMTP to send all outgoing email through this relay (Server Admin>Mail>Settings>General>
Rely outgoing mail through host: smtp.comcast.net:587
         Authenticate to rely with user name: user
I get the SMTP error:
SASL authentication failed: cannot authenticate to server smtp.comcast.net[76.96.62.117]: no mechanism available
There are no toggles on Server Admin to specify TLS or SSL or anything for authentication.
Does anyone know how to tell Server Admin how to authenticate an SMTP relay to smtp.comcast.net using TLS, which is apparently what comcast expects?

Answer 1

Wow, this is an obscure solution, but it works. According to this thread, the problem is that:
Although Comcast advertises "AUTH LOGIN PLAIN", the Postfix SASL library won't do plain text auth by default. It needs to be told it's okay with:
smtp_sasl_security_options = noanonymous
Solution:
$ su -
$ cd /etc/postfix
$ cp main.cf main.cf.no_smtp_sasl_security_options
$ echo 'smtp_sasl_security_options = noanonymous' >> ./main.cf
$ serveradmin stop mail
$ serveradmin start mail
I'm not sure how often /etc/postfix/main.cf is overwritten, but presumably this happens every time you change and save Mail settings in Server Admin, so you must redo these steps every time you change the Mail server if you want to use smtp.comcast.net as your mail relay.
AAPL, would you please add a toggle to handle this in Server Admin?