in reply to Compress email attachments
Since you know about MIME::Parser, you have MIME-tools (that's where MIME::Parser comes from). The documentation for MIME-tools gives examples for decoding and encoding MIME-formatted messages. All you need is a compression step in the middle. Have a look at Compress::Zlib.
Now try this out and if you have problems, come back with sample code and a description of what works and what does not work.
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Seekers of Perl Wisdom