Mac Mail Can't Connect to Comcast Outgoing Server

Hello all. About a month ago the Mail app on my Macbook became unable to contact the outgoing Comcast email server. I am able to send email via the Xfinity website and on my iPhone with same settings 7 password, but not the laptop. I am able to receive emails on the laptop. I carefully checked all settings but they are as prescribed. My Mac Mail is version 11.4 (3445.8.2) and I am running High Sierra Version 11.4 (3445.8.2). Any advice?

Here are the details from Connection Doctor, in case that helps.

WROTE Jun 26 15:16:02.689 [kCFStreamSocketSecurityLevelTLSv1_2] -- host:imap-mail.outlook.com -- port:993 -- socket:0x604000aa2400 -- thread:0x604005e64440

385.2 IDLE

READ Jun 26 15:16:02.749 [kCFStreamSocketSecurityLevelTLSv1_2] -- host:imap-mail.outlook.com -- port:993 -- socket:0x604000aa2400 -- thread:0x604005e64440

+ IDLE accepted, awaiting DONE command.

WROTE Jun 26 15:16:02.750 [kCFStreamSocketSecurityLevelTLSv1_2] -- host:imap-mail.outlook.com -- port:993 -- socket:0x6040024b5300 -- thread:0x604006271c40

5.118 LOGOUT