You don't refer to the package name consistently in the docs. Or rather, you do, but you consistently refer to it as "gmail" (all lc) rather than "Gmail".
When formatted via perldoc or similar, the formatting of the same code is a little wacky. Not sure why this is... the code seems to display OK in my browser, but maybe you are using tabs rather than more conventional 4-space indenting?
When fetching message info, Gmail is apparently escaping the < and > characters. You might want to look at those strings when you get the data back and clean them up a bit, just as an ease to users.
Snippets of code should be wrapped in
<code> tags not<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor