Symptoms

Postfix milter is not working properly. ' /var/log/maillog ' contains the following message:

postfix/smtpd[3089]: warning: milter inet:127.0.0.1:12768: can't read SMFIC_RCPT reply packet header: Connection timed out

Cause

Incorrect milter protocol version.

Resolution

1. Check ' milter_protocol ' version:

   # postconf milter_protocol
   milter_protocol = 2
   

2. Change ' milter_protocol ' value to '6' in ' /etc/postfix/main.cf ' and reload Postfix:

   # postfix reload