[imp] PGP/MIME vs OpenPGP

[A]

I realize that this is not particularly an IMP issue, but any help  
would be appreciated. I have exhausted the search in the mail list.

I prefer encrypted mail, and use IMP 4.2 (from Groupware Mail Edition)  
to successfully encrypt email to most of my contacts. However, many of  
my contacts that use the Hushmail web interface to read encrypted mail  
from me only see an attachment. Those using hushmail through a desktop  
client have no problems.

The Horde list search came up with an explanation, which basically was  
that IMP sends encrypted email strictly by RFC standards which  
hushmail apparently does not support.

I contacted hushmail support, and received an answer:

"The encryption format appears to be
PGP MIME. The Hushmail web interface is limited to only supporting Open
PGP. This is most likely the reason you can not decrypt the email
correctly. PGP MIME may be available in future versions of Hushmail. I
will add you to a list of interested users. As you have realized
Thunderbird + Enigmail have no problems decrypting the mail so you will
have to use this as the way to decrypt this mail."

I do not understand the difference between PGP/MIME and OpenPGP; Where  
can I get specific details on the differences?

-- 
I prefer the privacy of encrypted email. My public key is attached.



-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-keys
Size: 1332 bytes
Desc: PGP Public Key
URL: <http://lists.horde.org/archives/imp/attachments/20081114/34763cf4/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: PGP Digital Signature
URL: <http://lists.horde.org/archives/imp/attachments/20081114/34763cf4/attachment-0001.bin>