Updating offline disk cache gmail
First backup the Mail folder from your user folder: ~/Library/Mail Then go into the preferences of mail and select the account section and the specific account on the left and hit the minus sign on the bottom. Since it's IMAP everything should come back and it should work normal from there.
If you are missing anything you can recover it from the backup.
When it comes to taking up a bunch of disk space, the typical culprit is temp files. From there you can delete temp files, downloads, the recycle bin, and also previous versions of Windows if it exists.
Of course, you’ll find the previous version file after doing a major update like last year’s November update or the upcoming Anniversary update this summer.
Relaunch Mail and see if the spinning persists for more than 5-10mins.
Thanks I'm having roughly the same problem as you people.
Since last night, when I click on Get Mail, nothing happens. When I send emails from Mail app, it just sends for a very long time and the sendee ends up receiving multiple mails.
Verify everything is checked EXCEPT "Store draft messages on the server" (Having this checked has caused issues for some where Mail will spawn draft messages). It only appears to be a problem on my Macbook with SL10.6.3 & Mail Version 4.2 (1078) and Gmail.
Save any changes you have made and then quit and relaunch Mail as see if the issue has been resolved. A desktop G4 with 10.4.11 which accesses the same Gmail account by imap is behaving perfectly normally.