See your previous post.

Which API do you mean?

If you "simply" want access to the mails, in the folders (well, tags), see IMAP.

If you want other API access, maybe tell us what API you really mean.

I apologize for not being clear enough. I'll try again. Gmail uses OAuth 2.0 based access. I can access it with simple SMTP/IMAP, but Gmail doesn't like it (it thinks I'm insecure). So, I want to do it in their way. They provide instructions on how to do it in Python, PHP, Ruby and other languages, but not Perl. I looked in cpan, and there seem to be some modules that claim to do the work, but I couldn't be sure they're what I need. So how would you access Gmail using their OAuth? what module would you use? or is there some other way?

Have you looked at what CPAN offers on OAuth modules? There are various that you could use if IMAP is not what you want to use.