We still need to PRINT occasionally
A criticism... relying on the browser and system print functionality seemed like a good idea, but it won't properly format multi-page emails.
A suggestion.... Spawn a new tab with just the content of the email without the full header then the system print dialog can handle it better,
You need a PRINT button to do this.
You can hit the P key to print an email, or you can open the email and select the Printer icon next to the From field.
If you still find that the issue is happening after doing one of these, please see this help page for troubleshooting:
Wynn Murrell commented
Why isn't there a print icon so I can print from email or word at will?