Here is a new version of Postfix, just released and I’ve got it tested on Snow Leopard and Lion on my test and production machines. This release contains a workaround for a problem that is fixed in Postfix 2.9.
- The postscreen daemon, which is not enabled by default, sent non-compliant SMTP responses (220- followed by 421) when it could not give a connection to a real smtpd process. These responses caused some remote SMTP clients to return mail as undeliverable.
The workaround is to hang up after sending 220- without sending the 421 “sorry” reply; this is harmless.
The complete fix involves too much change for a stable release: send the 220 greeting, wait for the EHLO command, then send the 421 “sorry” reply and hang up.


