Sorry, this is a known problem that has been tracked down to messages that have tables embedded in table cells. Unfortunately, that is not something you can easily determine or fix.

Maybe Yahoo's print-optimized layout changed for AT&T users recently? Either way, a fix won't be ready by tomorrow's release of Firefox 103, but maybe someone will have a suggested workaround -- other than using Edge.

My suggested workaround for anyone using both Yahoo mail and Firefox is to uninstall Firefox and check this support forum from time to time to see if the printing bug has been fixed. I have needed to switch to another browser to print travel itineraries, online event tickets, etc. for years now. Edge prints them fine as does Chrome. I buy into the whole community-supported browser thing -- free as in beer and free as in speech -- but I am tired of having to tell my wife that she can't print her own emails because it is too complicated and I need to do it for her.

Now at least I realize I am not alone and that this is not related to my computer or my skills. I, too, have to print most of my YAHOO mail from another device (like my phone) or a different browser. It only seems to be with YAHOO and Firefox. The one work around that seems to work is if I set the scaling to 35%, then I can get most of the document to print, but it is very small. Waiting patiently for a better solution.

No fix yet for printing Yahoo Mail messges, unfortunately. I mentioned a partial workaround in this thread: Save as PDF fails.