[Mimedefang] How to filter base64 subject

[scuba at centroin.com.br]

Hi all,

	How can I filter (content based) subject encoded in base64 like
this:

=?iso-8859-1?b?VmlhQGdyYSwgU29tYSwgUGhlbnRlcm1pbmUsIExldmkhdHJhLCBBbWJpZW4sIExPV0VTVCBDb3N0IEV2ZXIh?=

Or, how to decode it before pass to SA?

Thank you,

- Marcelo