It appears that Thunderbird 2.x has issues with yDecode multipart decoder.
It downloads messages twice unlike Outlook Express or Windows Mail and that appears to "confuse" yDecode and Thunderbird with it so the multipart message/image etc. don't show up as fully decoded but rather instead it shows only a first part of the messsage (even though yDecode downloaded the rest of the parts as well).
Fortunately there is a simple solution - so if you are using Thunderbird simply upgrade to 3.0 (currently beta 3) which seems to have this bug fixed and downloads messages only once as it is supposed to.
If you have any additional questions or comments feel free to contact us.
