Fortunately, iPhone Mail can enlarge tiny fonts automatically and make your email experience a lot more legible.
Make iPhone Mail Use a Minimum Text Size for Displaying Emails
To define a minimum text size for messages in iPhone Mail:
- Tap Settings on the iPhone Home screen.
- Choose Mail, Contacts, Calendars (or Mail in iPhone Mail 1).
- Tap Minimum Font Size.
- Tap the desired size to which smaller (plain) text will be magnified automatically.
- Press the Home button.
In later versions of iOS (4+), you can specify larger text across many built-in applications — including Mail.
(Updated September 2012)