Hi,

We cannot get stunnel SMTP to work with Office 365 mail server. We are using Stunnel  5.13 and below are the config file content and the the client PC logs. The mail server logs do not reveal anything more.

Two observations of the test setup:

1) Using e.g. Mozilla Firebird mail client directly SLL/SMTP on the same PC connection to same Office 365 mail server works ok, but via Stunnel it outputs the error log below.

2) Also, on the same PC, SSL/SMTP connection via stunnel to Gmail server works ok.

Stunnel conf-file:

==============

output = stunnel_log.txt

debug = debug

cert = tstunnel.pem

client = yes

[SSMTP]                                                                     

accept =  127.0.0.1:54500                                                                 

connect = xxx.xxx.xxx.xxx:587 (Hannu V: removed IP address from this mail)

protocol = smtp                                                                                   

Client PC logs:

===========

2015.04.28 09:17:36 LOG7[ui]: No limit detected for the number of clients

2015.04.28 09:17:36 LOG5[ui]: stunnel 5.13 on x86-pc-msvc-1500 platform

2015.04.28 09:17:36 LOG5[ui]: Compiled/running with OpenSSL 1.0.2a 19 Mar 2015

2015.04.28 09:17:36 LOG5[ui]: Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI

2015.04.28 09:17:36 LOG7[ui]: errno: (*_errno())

2015.04.28 09:17:36 LOG5[ui]: Reading configuration from file tstunnelSmtp_SAUX1_0.conf

2015.04.28 09:17:36 LOG5[ui]: UTF-8 byte order mark not detected

2015.04.28 09:17:36 LOG5[ui]: FIPS mode disabled

2015.04.28 09:17:36 LOG7[ui]: Compression disabled

2015.04.28 09:17:36 LOG7[ui]: PRNG seeded successfully

2015.04.28 09:17:36 LOG6[ui]: Initializing service [SSmtp]

2015.04.28 09:17:36 LOG6[ui]: Loading certificate from file: tstunnel.pem

2015.04.28 09:17:36 LOG6[ui]: Loading key from file: tstunnel.pem

2015.04.28 09:17:36 LOG7[ui]: Private key check succeeded

2015.04.28 09:17:36 LOG7[ui]: SSL options: 0x03000004 (+0x03000000, -0x00000000)

2015.04.28 09:17:36 LOG5[ui]: Configuration successful

2015.04.28 09:17:36 LOG7[ui]: Listening file descriptor created (FD=448)

2015.04.28 09:17:36 LOG7[ui]: Service [SSmtp] (FD=448) bound to 127.0.0.1:8030

2015.04.28 09:17:36 LOG7[ui]: Service [SSmtp] accepted (FD=456) from 127.0.0.1:54500

2015.04.28 09:17:36 LOG7[ui]: Creating a new thread

2015.04.28 09:17:36 LOG7[ui]: New thread created

2015.04.28 09:17:36 LOG7[0]: Service [SSmtp] started

2015.04.28 09:17:36 LOG5[0]: Service [SSmtp] accepted connection from 127.0.0.1:54500

2015.04.28 09:17:36 LOG6[0]: s_connect: connecting xxx.xxx.xxx.xxx:587    (Hannu V: removed IP address from this mail)

2015.04.28 09:17:36 LOG7[0]: s_connect: s_poll_wait connecting xxx.xxx.xxx.xxx:587    : waiting 10 seconds (Hannu V: removed IP address from this mail)

2015.04.28 09:17:37 LOG5[0]: s_connect: connected connecting xxx.xxx.xxx.xxx:587    (Hannu V: removed IP address from this mail)

2015.04.28 09:17:37 LOG5[0]: Service [SSmtp] connected remote server from yyy.yyy.yyy.yyy:54503 (Hannu V: removed IP address from this mail)

2015.04.28 09:17:37 LOG7[0]: Remote socket (FD=472) initialized

2015.04.28 09:17:37 LOG7[0]:  <- 220 NNN.outlook.office365.com Microsoft ESMTP MAIL Service ready at Tue, 28 Apr 2015 14:17:38 +0000

2015.04.28 09:17:37 LOG7[0]:  -> 220 NNN.outlook.office365.com Microsoft ESMTP MAIL Service ready at Tue, 28 Apr 2015 14:17:38 +0000

2015.04.28 09:17:37 LOG7[0]:  -> EHLO localhost

2015.04.28 09:17:37 LOG7[0]:  <- 250-NNN.outlook.office365.com Hello [xxx.xxx.xxx.161] (Hannu V: removed IP address from this mail)

2015.04.28 09:17:37 LOG7[0]:  <- 250-SIZE 157286400

2015.04.28 09:17:37 LOG7[0]:  <- 250-PIPELINING

2015.04.28 09:17:37 LOG7[0]:  <- 250-DSN

2015.04.28 09:17:37 LOG7[0]:  <- 250-ENHANCEDSTATUSCODES

2015.04.28 09:17:37 LOG7[0]:  <- 250-STARTTLS

2015.04.28 09:17:37 LOG7[0]:  <- 250-8BITMIME

2015.04.28 09:17:37 LOG7[0]:  <- 250-BINARYMIME

2015.04.28 09:17:37 LOG7[0]:  <- 250 CHUNKING

2015.04.28 09:17:37 LOG7[0]:  -> STARTTLS

2015.04.28 09:17:37 LOG7[0]:  <- 220 2.0.0 SMTP server ready

2015.04.28 09:17:37 LOG6[0]: SNI: sending servername: NNN.office365.com

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): before/connect initialization

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv2/v3 write client hello A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 read server hello A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 read server certificate A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 read server key exchange A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 read server certificate request A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 read server done A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 write client certificate A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 write client key exchange A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 write certificate verify A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 write change cipher spec A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 write finished A

2015.04.28 09:17:37 LOG7[0]: SSL state (connect): SSLv3 flush data

2015.04.28 09:17:37 LOG3[0]: SSL_connect: Peer suddenly disconnected

2015.04.28 09:17:37 LOG5[0]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket

2015.04.28 09:17:37 LOG7[0]: Remote socket (FD=472) closed

2015.04.28 09:17:37 LOG7[0]: Local socket (FD=456) closed

2015.04.28 09:17:37 LOG7[0]: Service [SSmtp] finished (0 left)

--- Hannu