Using Outlook 365 I can receive emails from my comcast email account but i cannot send emails through outlook

Hi there, @user_qf0l7j I'm sorry to hear about the trouble you are experiencing with your email. You're likely encountering an issue with your outgoing SMTP server settings in Outlook 365 when trying to send emails from your Comcast account. To resolve this, you'll need to ensure your outgoing server (SMTP), settings are correctly configured in Outlook. Specifically, verify the SMTP server address, port number, and encryption method align with Comcast's recommendation.-Richard

@user_qf0l7j If you check the pinned posts here, you'll see a note about DMARC policy.  The domain comcast.net now has a DMARC policy of reject for the domain and subdomains. In nearly all cases, this means you cannot use that domain when you send through an outside platform.

I had this issue and it required clearing the outlook cache

it then worked