[imp] multipart/alternative text/plain problems

[Jethro Beekman]

Hello all,

I have problems with IMP not displaying the text/plain part of an
e-mail for once. It just doesn't show up at all, there is just a box
featuring 'alternative parts'. The HTML part with embedded image works
just fine. I am using Zend_Mail to send the mail. When I compare such
an e-mail with one Horde makes itself, I really can't see any
difference except for different Content-Transfer-Encoding which IMHO
shouldn't matter.

The two mails without irrelevant headers are:
http://jbeekman.nl/mail_zend.txt
http://jbeekman.nl/mail_horde.txt

Oh and I forgot to mention: it works just fine in Thunderbird and  
Roundcube Webmail.

I hope someone can tell me what's wrong here.

Best regards,
Jethro Beekman