smtp from application fails to send

i have an application that has smtp settings configured to send email alerts and was working for 1+ years until a month or so ago.

I was connecting to this smtp:   smtp.w14b.comcast.net   port 465   SSL

It fails to send emails now.  I have a XXX@YYY.comcastbiz.net email account.

Do i need to do the migration to 365? as referenced here:  https://business.comcast.com/help-and-support/internet/set-up-existing-domain-in-microsoft-office-365/

or is there an easier way to get this working?

Thanks.