How to set up ssmtp mail for microsoft exchange?

Question

ubuntu

Please help.
There is a server that should send letters through the mail server within the company.
domain.ru - ubuntu 14.04 with ssmtp
mx2.domain.ru - Windows exchange server
Registered all configs in ssmtp settings.
Still getting:
[<-] 220 mx2.domain.ru Microsoft ESMTP MAIL Service, Version: 6.0.3790.4675 ready at Fri, 24 Apr 2015 16:52:22 +0300
[->] EHLO 37.19.6.21
[<-] 250 OK
[->] STARTTLS
[<-] 554 5.7.3 Unable to initialize security subsystem
send-mail: Cannot open mx2.domain.ru:25
Where to look? Where is the mistake? Or I didn't do something...

Answer 1

Change the port to 465 if you are going to use encrypted smtp. And then you somehow break into the 25th, and judging by the exhaust - with TLS turned on.