IMAP + Outlook2013 + Optimum isp: can't send emails

IMAP + Outlook2013 + Optimum isp: can't send emails

Can't send emails using zoho smtp through Optimum (cablevision) servers. Tried optimum smtp but that fails too.

Outgoing Server Settings: 

Outgoing Server Name: smtp.zoho.com
Port: 465
Require SSL: Yes
Require Authentication: Yes