How can I keep a line from breaking on my template, such as a email address?

If you wrap some text in a <STYLERUN> with the attribute 'wrap=false', then nothing inside that tag will wrap at all. 
<STYLERUN wrap='false'>Email is: @email@</STYLERUN>
will always have the full "Email is:" on one line, truncating to fit if needed.

This is only helpful with HTML or VB scripted fields, not direct Text Box or Rich Text fields.

wrap='false' can also be used with <P>, <FONT> or <SPAN> tags.

IMPORTANT: Using wrap='false' completely invalidates force fit. When any part of the script contains wrap=false, the mechanism for telling force fit that the text doesn't fit yet, is turned off. So force fit can't be used with wrap='false'.
Users frequently desire to use force fit to shrink a field while preventing any lines from breaking into two. There is no way to accomplish this. Wrap='false' plus force fit will not do it at all.