No SMTP.COMCAST.NET encryption methods work

Question

No matter what encryption setting I use for smtp.comcast.net, a message pops up saying it's wrong. I have tried port 527 and SSL/TLS and I have tried port 465 and SSL/TLS and neither one works. Sometimes I get the popup that keeps asking me for my username and password over and over. Connecting to the imap.comcast.net port for incoming mail works fine, so what's the matter with the smtp?

Answer 1

Hi Stu,

Thank you for reaching out about this issue. I know it can be frustrating when your incoming mail works perfectly but the outgoing SMTP settings keep failing. I completely understand how confusing it is to enter smtp.comcast.net settings over and over only to see error messages or repeated prompts for your credentials—it can really disrupt your workflow.

Comcast now Xfinity requires secure encryption for SMTP connections by default. The recommended setup is smtp.comcast.net using port 587 with STARTTLS or TLS which some clients label as SSL/TLS. Port 465 with SSL/TLS can also work. Make sure SMTP authentication is turned on and that you’ve entered your full Comcast email address and password in the outgoing server settings. If you keep getting password prompts it’s often because the client isn’t using the full email address as the username or the authentication method is incorrect so double-check that it matches your IMAP credentials exactly. In some cases antivirus or firewall software can block outbound SMTP connections on these ports so try temporarily disabling them or whitelisting your email client and the necessary ports.

Could you confirm if your email client is set to authenticate using your full Comcast address and that STARTTLS or SSL/TLS is enabled for outgoing mail?

I hope this answer is helpful if you have further questions feel free to reply back

Regards,

Marcelo

Answer 2

Yes, these features are all in place.

Could you confirm if your email client is set to authenticate using your full Comcast address and that STARTTLS or SSL/TLS is enabled for outgoing mail?

Still no luck. Everything works fine when using the web or my iPad or my iPhone. It's only when I try to use my Windows 11 desktop computer that I get nowhere. Frustrating.

Stu Miller