How do I enlarge text for all emails?

Hi

One of my IT clients is visually impaired, and he has a hard time reading small text.

I have managed to enlarge some of the emails, but some namely that have been preformatted, and are not just plain text are still small.

Is there any way to enlarge the text on all emails?

Thanks

Right-click in the message body and choose Zoom.

The zoom level will be remembered across restarts.

Will the newly enlarged text also be visible when the email is printed?