[Dovecot] Problems with Apple Mail and attachments

[Helga Mayer]

Hello,

has anyone experiences with the Apple mail client, to be precise : Mail 5.2?
When I copy a message with an attachment from the inbox to a different  
folder using 'move' or 'copy' , Apple Mail does not properly display  
the attachment in the new folder.

When I copy the same message using 'archive' the attachment shows up properly.
There is no difference on the server side. We are using maildirs. The raw
messages in the various folders are identical.
Deleting plist on the Mac didn't help.
After removing and recreation of the account (client side) the  
attachments are displayed correctly again.

Is this an apple problem or has it got anything to do with  
dovecot.index.cache ?

Kind Regards
Helga Mayer