When SOGO is trying to send any smtp message the process is stopping with folowing error message. "Oct 29 18:140733193388075:140527034957876 sogod [1167]: [ERROR] <0x0x7fcf30f93830[SOGoMailer]> Could not connect to the SMTP server XXX.XXX.XXX.XXX on port 25".
Here is the output of debug log:

C: connect to <0x0x7fcf30f9f430[NGInternetSocketAddress]: host=XXX.XXX.XXX.XXX not-filled>
S: <SMTP-Reply: code=220 line='mail1.xxxxx.xx ESMTP'>
C: EHLO dav.xxxx.xxx
S: <SMTP-Reply: code=250 line='DSN'>
S: pipelining extension supported.
S: size extension supported.
S: plain auth extension supported.

Here is the output of tcpflow:

XXX.XXX.XXX.002.00025-XXX.XXX.XXX.005.56486: 220 mail1.xxxxx.xx ESMTP

XXX.XXX.XXX.005.56486-XXX.XXX.XXX.002.00025: EHLO dav.xxxx.xxx
XXX.XXX.XXX.005.56486-XXX.XXX.XXX.002.00025:

XXX.XXX.XXX.002.00025-XXX.XXX.XXX.005.56486: 250-mail1.xxxxx.xx
250-PIPELINING
250-SIZE 45000000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH LOGIN PLAIN
250-AUTH=LOGIN PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

Enviroment:
SMTP Server: Postfix 2.7.1 (standard setup, requires smtp auth)

Sogo settings:
SOGoMailingMechanism = smtp;
SOGoSMTPAuthenticationType = plain;
SOGoSMTPServer = smtp.xxxxxx.xxx;