SASL authentication failed; cannot authenticate to server smtp.comcast.net
I'm a Unix sysadmin and I run my own SMTP server. I have a DSL modem, which connects to a firewall, which connects to a SMTP server. For outbound email, Postfix goes through smtp.comcast.net:587, and authenticates using SASL.
This setup has been working fine for years. However, over the past 2 weeks, I've been experiencing sporadic problems. It appears the SASL auth sometimes fails, but eventually succeeds. This typically delays my outbound email by about 6 to 12 hours.
Is anyone else seeing this? Here's the full message from Postfix:
May 24 00:07:45 ebola postfix/smtp: warning: SASL authentication failure: No worthy mechs found
May 24 00:07:45 ebola postfix/smtp: 50A7C1873C5: to=, relay=smtp.comcast.net[22.214.171.124]:587, delay=19763, delays=19763/0.09/0.07/0, dsn=4.7.0, status=deferred (SASL authentication failed; cannot authenticate to server smtp.comcast.net[126.96.36.199]: no mechanism available)