|Think about Loose Coupling|
the organization I work for has some years ago deployed a webmail client (developed by an outside person who is no longer available).
I'd prefer if the webmail was written in Perl (rather than PHP or JSP as most of the candidates are) because I like Perl better than those other languages.
Why does the language matter, if you want a solution that works well? SquirrelMail works. So does IMP. You don't need to be a PHP expert to install either of them.
I'd need to patch PHP's IMAP code. Not a pretty task.
And all this time, I thought PHP was too easy. The training wheels without the bike, etc, etc.
Also, PHP may still have security vulnerabilities quite apart from those that come with the webmail itself.
And Perl is unreadable and not object-oriented. Not to mention that you cannot mix Perl code with HTML. (Have I forgotten any other false stereotypes?)