How are you deploying the changes to your program wrapping the mail command? Perhaps you're using ftp, sftp, scp, rsync, or something similar? Chances are any of the pure-Perl mail sending modules could be deployed the same way.

Some of those mail sending modules even just wrap a Sendmail mail submission executable (or the mock sendmail executables offered for compatibility by any of Postfix, Exim, qmail, SMail, or a long list of others) usually found at /usr/sbin/sendmail, /usr/bin/sendmail, or (for hysterical porpoises) /usr/lib/sendmail. The trick is, they wrap it properly so you don't have to. They let you just call a simple sub from your Perl program so you don't have to sweat the details.

If you really want to wrap an external program, consider a module that does so. If you can't stand the thought of a module, consider grabbing the code from one and crediting the author. That would let you just update the one file on those servers instead of two.

I generally use my own interface module around Net::SMTP::TLS and have hacked support for that module into NMS formmail, too. However, you might prefer Mail::Mailer, Mail::Sendmail, MIME::Lite, or Mail::DWIM (which is one of those that will wrap around a Sendmail mail submission executable).

Update: fixed a typo in PM link tag for Mail::DWIM