GO!NotifyLink Enterprise Server:
When a user sends an email with an attachment through Apple Mail it is not available to download on the device.
This is an issue with IMAP formatting through Apple Mail. The format of the message that Apple Mail is creating is incorrect. Per spec, when an attachment name contains spaces, the file name should be put within quotation marks in the MIME header and this is not happening. If there is no space in the file name, all should work as expected.
Through some research on this problem we have found some hope that this could be corrected in 10.5.2/Leopard with Mail v. 3.2. We do not have confirmation directly from Apple to acknowledge this as their bug, but we have found reference to it in user forums. The second link below states that the issue appears to be resolved in 10.5, but we did not find this to be the case. We can only assume that the poster tested with filenames that contained a single space. When using 10.5, we found that only filenames that contain a single space are now working correctly. If a filename contains multiple spaces, the bug still exists and results in the behavior where the attachment is named EmailvCard.txt and cannot be retrieved.
This link refers to the problem from gmail users:
This link mentions that it appears to be fixed in 10.5: