Outlook 2016 for Mac unable to make secure connection to server

Hey there ! Thanks for reaching out. Have you confirmed all the settings are correct for your clientt? https://comca.st/3dxtGR5

• Incoming Mail Server Name: imap.comcast.net
• Incoming Mail Server Port Number:
  • Recommended: 993 with SSL ON
  • Only if Needed: 143 with SSL ON
• Outgoing Mail Server Name: smtp.comcast.net
• Outgoing Mail Server Port Number:
  • Recommended: 587 (SMTP)
  • Only if Needed: 465 (SMTPS)
• SSL Encryption: checked
• Authentication: XFINITY username and password required

No I was using mail.comcast.net and smtp.comcast.net.  I will try the addresses you listed. 

Exact same error Connection to the server failed or was dropped.

one caveat if the document has no attachments or the email is not listed as confidential it sends fine.  Just outlook keeps telling me that a secure connection could not be made.

https://forums.xfinity.com/t5/Internet/ANSWERED-How-to-Set-Up-Your-Comcast-Email-Address-with-an/ta-p/3258506

or

https://www.xfinity.com/support/articles/email-client-programs-with-xfinity-email

These will give you the correct information for server settings.

@finkel

Did you check the link I provided above to see if it applied to you?

@finkel   open up norton and disable the firewall and see if the problem goes away.

@user_056e0a  Thank you for your post!  I was having the same issue.  Disabling Norton firewall did indeed resolve my problem.  Hopefully Norton and MS can get together and resolve this.