On 16 Sep 2014, at 18:18, Philip Prindeville wrote:
MIMEDefang allows you to do all this, plus you can call Perl modules
like File::Type on attachments to figure out if the file has been
mistyped (i.e. the content-type disagrees with what the actual file
header and/or file extension says it is).
Other reasons to use MD for this:
1. It analyzes the MIME structure of messages and interprets header
attributes so you don't need to figure out a complex RE to match all of
the edge & corner cases of legal MIME headers and don't need to test a
complex RE against every logical header.
2. Optionally, you can have it unpack zip archives and check the files
inside.
3. It has robust, mature support for SpamAssassin & a long list of AV
tools so you can put lightweight policy enforcement like this (or other
conditional diversions) before passing messages to the more demanding
deep scanners.
