Alright, using postconf debug_peer_list appears to have identified the issue:
Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-enceladus.<mydomain>.net Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-PIPELINING Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-SIZE 104857600 Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-ETRN Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-STARTTLS Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-ENHANCEDSTATUSCODES Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250-8BITMIME Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 250 DSN Mar 14 14:03:10 enceladus postfix/smtpd[26760]: watchdog_pat: 0x564edfaa6dc0 Mar 14 14:03:10 enceladus postfix/smtpd[26760]: < n5.nabble.com[162.253.133.81]: MAIL FROM:<boun...@n2.nabble.com> SIZE=3488 Mar 14 14:03:10 enceladus postfix/smtpd[26760]: > n5.nabble.com[162.253.133.81]: 530 5.7.0 Must issue a STARTTLS command first I modified the following: main.cf - smtpd_tls_security_level = encrypt CHANGED TO may master.cf - -o smtpd_tls_security_level = encrypt CHANGED TO may Mail from (in this case nabble) is now delivered properly. I'm hopeful that this is my root issue...I will need to continue to monitor. Thank you all very much for your help! -- Sent from: http://postfix.1071664.n5.nabble.com/Postfix-Users-f2.html
