Using Outlook 365 outgoing email does not reach the person though email is showing up in Sent folder

Use email for personal use only, no business or mass mailings.

On Xfinity wifi - from web portal I can send and recevie emails.

On Xfinity wifi - from Outlook 365, I can receive emails, though all sent emails show up in the Sent folder but no one recevies the emails.  Have sent emails to gmail, hotmail and others and are not being received.  Can send emails from gmail and hotmail and they will go through.  Emails sent from my comcast.net account are not being delievered.

Rebooted the Xfinity modem I am renting, rebooted laptop - no change.

Incoming: impa.comcast.net  - Port 993 - SSL

Outgoing: smtp.comcast.net - Port 465 - SSL

Is it possible there is a block, if so, how does it get removed?