RFC 1741 describes the BinHex 4.0 format.
Please note the following sentences:
*Only when available software
*and/or user practice dictates, should this method be employed. It is
*recommended to use application/applefile [FALT94] for maximum
*interoperability.
*AppleDouble file format [APPL90], encoded in MIME as
*multipart/appledouble [FALT94] and application/applefile [FALT94] is
*the preferred format for a Macintosh file that is to be included in
*an Internet mail message, because it provides recipients with
*Macintosh computers the entire document, including Icons and other
*Macintosh specific information, while other users easily can extract
*the Data fork (the actual data).
*Documents which lack a data fork must be sent as AppleSingle
*according to RFC 1740 [FALT94].
*Unless there are strong reasons not to, all other documents should
*be sent as AppleDouble according to RFC 1740 [FALT94]. This
*includes documents with non-trivial resource forks, and documents
*without corresponding well-known MIME types.
Also note that the name of the file should include the ".hqx" extension as
in:
*3a. BinHex example
* Content-Type: application/mac-binhex40; name="car.hqx"
Some popular email providers seem to have missed these important points.
-----
Chris Newman <chrisn+(_at_)cmu(_dot_)edu>,
http://www.contrib.andrew.cmu.edu/~nifty/
The worst thing about censorship is: [censored]