This might happen with other email hosts, but I've only ever gotten the call to fix a Gmail account. (And really, why would you use another email host?) Mail will choke on that big message, and prevent you from receiving any more of your Gmail. I've fixed it multiple times before, but thanks to Glenn for digging up this more consistent and reliable fix.
———- Forwarded message ———-
From: Glenn Anderson
Date: Tue, Feb 15, 2011 at 7:01 PM
Subject: recovered messages folder
To: Jonathan Marcus
"Recovered Messages" mailbox in Apple Mail
(for Gmail account that chokes on large attachment)
1.Take the Gmail account offline from within Mail and delete the Recovered Messages folder.
2. Make invisible files visible
4. Delete all the data within .OfflineCache folder – do not delete the folder.
5. Close Mail application and reopen.
Alternatively, you can find that .OfflineCache folder via Terminal.
Gmail Maximum attachment size
With Gmail, you can send and receive messages up to 25 megabytes (MB) in size.
You may not be able to send larger attachments to contacts who use other email services with smaller attachment limits.
Posted via email from J2 Tech Blog