First, know that ISP email server configurations and know them well. Verify the smtp server info and the login and alternate ports and so on. As a test, use an email client like thunderbird and verify you can connect. That will confirm your settings. Now use those settings in OG.
Since OG is ongoing work you must be sure the issue is with OG and not someplace else. So I would start there. Needless to say always run the latest version.
Mine works fine using OG 153 but I know all my ISP's smtp and pop info.