This may be over-obvious, but how about Net::SMTP? I mean if you're just sending mail through an SMTP server, Net::SMTP will provide the same functionality on both..
Rich
Comment on Re: SMTP Modules that are both Win32 and Unix compliant
I just completed a similar project using Net::SMTP.
I also got a great example from this excerpt from Programming with Perl Modules.
I'm not sure about it's compliancy with Win32 although I kinda recall seeing a script that used it sometime ago for WinNT.