I have the same problem. The incoming works but the outgoing doesn't. For incoming I use my account name, pop3, password, mail.optonline.net, port 110 no security but logon. The outgoing I have tried mail.optonline.net port 25 and smtp.optonline.net port 25 no security. I have tried with security SSL port 587. No joy. This is really going to suck if somehow this is blocked like in hotels where you can't reply to email messages without going to optonline.net webmail. I do have a gmail account but I do not want to live there for emails.
Any thoughts and/or recommendations.
Change your outgoing port to 587.
Oh and the outgoing should be mail.optonline.net. Apparently when they made the change from SMTP.optonline.net they blocked the port 25.
Google is your friend.