Hello WayneMunney,
I'm John an Independent Advisor and a Microsoft user like you. I'll be happy to assist you today. I understand you have a problem with Mail app on Windows 10 prints small.
There are several reports from other users who are facing the same problem. This can be an issue with the Mail app itself. One user already tried and performed Windows 10 Mail app troubleshooting methods, Uninstall recent updates and even performing a System Restore on an earlier date without fixing the issue.
As a workaround, I would recommend you to setup/login your email with either a browser or Thunderbird and print from there depending on your preference/email source, as the Mail app is buggy right now.
I also recommend reporting this issue through the Feedback Hub app to notify Microsoft and hope they will release a fix soon.
https://support.microsoft.com/en-us/windows/sen....
Kindly let me know if this helps or if you have any further concerns.
Sincerely
John DeV
Independent Advisor