Hi not sure why this happens, but looks like lmtp_rawlog_dir blocks the successful negotiation of an lmtp starttls connection. Reproducible with openssl s_client.? Two runs with only difference the presence of lmtp_rawlog_dir setting in dovecot config. Failed connection with lmtp_rawlog_dir Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Connect from ::1 Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL: where=0x10, ret=1: before SSL initialization Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL: where=0x2001, ret=1: before SSL initialization Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL: where=0x2002, ret=-1: error Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL error: SSL_accept() failed: error:1408F10B:SSL routines:ssl3_get_record:wrong version number Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Error: lmtp-server: conn [::1]:53876 [2]: SSL handshake failed: SSL_accept() failed: error:1408F10B:SSL routines:ssl3_get_record:wrong version number Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Debug: SSL error: SSL_accept() syscall failed: Invalid argument Dec 10 21:01:31 server03 dovecot[41002]: lmtp(41021): Disconnect from ::1: SSL Initialization failed (state=READY) Successful connection without lmtp_rawlog_dir Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Connect from ::1 Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x10, ret=1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: before SSL initialization Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL_get_servername() failed Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS read client hello Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write server hello Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write change cipher spec Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: TLSv1.3 write encrypted extensions Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write certificate Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: TLSv1.3 write server certificate verify Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write finished Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=-1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: TLSv1.3 early data Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS read finished Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x20, ret=1: SSLv3/TLS write session ticket Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write session ticket Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2001, ret=1: SSLv3/TLS write session ticket Dec 10 20:59:07 server03 dovecot[40970]: lmtp(40988): Debug: SSL: where=0x2002, ret=1: SSL negotiation finished successfully John