If you are having problems sending e-mail through Comcast, Verizon, or another third party, we have two tutorials available which should resolve your issue.
1) Check your e-mail program to make sure SMTP Authentication is enabled, or turned On. You will need to enable this setting on every computer you are using to send e-mail from. In layman's terms, SMTP Authentication (Simple Mail Transfer Protocol Authentication) is a way to check and verify who you are before sending out e-mail, in an effort to help prevent e-mails being sent anonymously and cut down on spam.
If you are having difficulties sending out e-mail, please see the "How do I enable SMTP Authentication?" tutorial to check that your SMTP Authentication setting is enabled, or turned On.
2) If you have already checked and made sure that SMTP Authentication is enabled and are still having difficulty sending e-mail, you may need to change your SMTP port setting. In layman's terms, certain Internet Service Providers (ISPs) intentionally block the default SMTP communication port as an attempt to reduce the amount of spam coming from their network. This forces the ISP's customers to either send mail through the ISP's mail servers, or to change the configuration of their email program(s) in order to send mail through external mail servers.
If you are still having difficulties sending out e-mail, and have already walked through the "How do I enable SMTP Authentication?" tutorial, please see our "How do I change the SMTP port in my Email client?" tutorial to change your SMTP port setting to 587.