[Mimedefang] Curious about a couple of things in mimedefang-filter

[Jim McCullars]

Just for my own curiosity, what does MD consider SuspiciousCharsInHeaders
and why are they dropped?  Also, what is the danger of curlies in file
names?  And what about non-alpha chars in an extension?  The sample filter
drops all of these.

Second question:  Is it possible to get the string that the sending MTA
sends as the HELO value?  I have noticed that a lot of spam will have *my*
host name as the HELO host, and I would like to reject the connection
unless it's really my host sending the mail.  Thanks!

Jim