Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Mail on my watch is pretty much unusable - not because of text, but because it takes absolutely ages to refresh with new mail.
 
The workaround:

Use Outlook for mail on your iPhone/Watch.

Email is MUCH more legible, and I think it's absurd that Apple hasn't addressed this.

My Mail complication is now Outlook, and I'm getting notifications from Outlook, instead of mail, on my iPhone/Apple Watch.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.