[horde] Horde fails to detect GPG encrypted mails from Enigmail and APG

[Michael]

Hi,
I'm having troubles decrypting mails that are not coming from IMP.
Mails from Enigmail (Thunderbird) and APG (K-9 Mail) are not  
recognized as GPG encrypted mails, which makes me impossible to  
decrypt it with IMP.

I put some samples to pastebin.

Mail from Enigmail in Text:
http://pastebin.com/TxrzqLE4

Mail from Enigmail HTML:
http://pastebin.com/ckbCAaN8

Mail from APG Text:
http://pastebin.com/EHwpwKFu

I've no troubles with mails coming from IMP.
Is there something I can do to make it work with at least Thunderbird  
and K-9 Mail?

IMP Version: 6.2.0
Horde Version: 5.2.0

Regards,
Michael