Postfix Error: "SASL authentication failure: No worthy mechs found".

Connecting a Postfix relay as an SMTP source in Flowmailer fails and shows the error: "SASL authentication failure: No worthy mechs found."

How to fix this:

  1. Install the Cyrus SASL, cyrus-sasl-lib and cyrus-sasl-plain packages;
  2. Add "smtp_cname_overrides_servername = no" to the postfix configuration or connect to front.flowmailer.net due to account name translation (CNAME is preferred);
  3. Allow for plain authentication;
  4. Reboot services to apply the configuration.