Globally Speaking

Line wrapping can vary noticeably between the sender's and receiver's versions of an email message because of differences in user settings, screen size, and other factors. You should pay careful attention to the right margin when you compose your email, or else your recipient might get awkwardly broken lines like those in the example below.

If you use a typewriter-mimicking font (such as Courier or Courier New), it's a fairly safe bet that a line of text which contains 60 characters (maximum) will not be split by the line-wrapping function of your recipient's software.

This is an example of awkward line wrapping that can occur
when your settings are
not read correctly by your recipient's email software. The
cause is usually
variations in user settings, but it is also possible that
the recipient's
software just cannot be adjusted to accommodate your
formatting.