If you’re a Comcast Internet residential customer you should be aware that they have recently announced several changes to their service. The most notable change is their decision to block port 25 and 2525 which are the main SMTP ports used to send email on the Internet.
According to the Comcast help and support website their reason for blocking is “To prevent spam and to ensure the security of our network and customers, Comcast no longer supports the use of port 25 for sending email. Port 25 is unsecured and Botnet spammers can use it to send spam.”
Most email clients by default use port 25 to send email, which means that if you’re not able to send outgoing email, but you can receive email, then you have probably been affected.
To fix this issue, simply go into your email settings and change your outgoing port to 465 and then make sure SSL is turned on. You will get a warning saying that you need to confirm the certificate, but once you accept everything you should be able to send emails without having issues.
If that doesn’t fix it please visit the Comcast email setup page and click on the email client you’re using.
Configure Your Email Settings to Comcast Email