I can confirm that this is really a bug in the Icedove. The source of the message (Ctrl+U) is cut off before the real end of the attachment but while downloading the contents of the message from IMAP server (Exchange) using IMAP command . fetch 1 (RFC822) I get the whole body of the message including complete attachment.
I have Icedove 2.0.0.9-3 but I have had the problem for a few weeks already (today I tried to update from version 2.0.0.6-X to fix it).
