I've setup a Postfix + Courier server and have a Rails app configured with the SMTP server settings. Whenever the Rails app tries to send an email, this is what appears in the Postfix log (additional log verbosity set in master.cf)
Feb 22 03:57:24 alpha postfix/smtpd[1601]: Anonymous TLS connection established from localhost[127.0.0.1]: TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)
Feb 22 03:57:24 alpha postfix/smtpd[1601]: smtp_get: EOF
Feb 22 03:57:24 alpha postfix/smtpd[1601]: match_hostname: localhost ~? 127.0.0.0/8
Feb 22 03:57:24 alpha postfix/smtpd[1601]: match_hostaddr: 127.0.0.1 ~? 127.0.0.0/8
Feb 22 03:57:24 alpha postfix/smtpd[1601]: lost connection after STARTTLS from localhost[127.0.0.1]
Feb 22 03:57:24 alpha postfix/smtpd[1601]: disconnect from localhost[127.0.0.1]
Feb 22 03:57:24 alpha postfix/smtpd[1601]: master_notify: status 1
Feb 22 03:57:24 alpha postfix/smtpd[1601]: connection closed
Any ideas as to why it's losing the connection after authentication?