The default port for Outbound SMTP is port 25. However your Internet service provider may be blocking outbound SMTP on that port. 


Outbound SMTP is supported the following ports:


Outgoing SMTP Server: outbound.mailhop.org
SMTP Port: 25 (default), 2525, or 10025
SMTPS (SSL/TLS): 465 (default) or 10465