Service-Related Emails from Comcast / Xfinity to multiple email accounts

I get duplicate Service-Related email messages from Comcast/Xfinity to ALL of my Comcast email accounts and some of my non-Comcast accounts. I have asked on occasion when I am on the phone with Customer Support if there is a way to narrow this down to one or even two Comcast accounts. I am told there is NOT.  I can NOT unsubscribe on any account from Service-Related emails as there is no link for this. It is bad enough I have to delete each message from each Comcast account, but I don't understand at all why Comcast feels authorized to send to my other accounts. Supposition: I recall providing TWO of my Comcast email addresses for two Xfinity services when I signed up for the services, so I get that. Of course, Comcast knows my other Comcast.net addresses. The non-Comcast addresses were almost certainly provided on request at login to Comcast before I realized how problematic this was and started declining to do so. Is there any way to get Comcast to reduce this burden? My next solution is going to be blocking Comcast/Xfinity messages to some of my email addresses at either the Comcast online email level or the email client level. These are not elegant solutions. If/when I leave Comcast, this will be one of the reasons.

Thanks for any assistance.