What makes you believe that? The reason I asked is that I seem to remember precisely this, a way to "delete all versions" of a given file from the TM backup. It was most likely unrelated to Mail. But I could not find any documentary on this on the Apple server - and, of course may be wrong. Do you have any positive evidence that it cannot be done?
Are you using Snow Leopard as stated in your signature?
If so, I'm afraid you can't do anything about it, other than wait until new backups overwrite the old ones.
But, if you are talking about Version Lion's feature, I don't think it is enabled for Apple Mail.
You can get rid of all or some version of a document only with applications that are "version" aware.
Sandy MacLane wrote:
How do I delete all versions of a file (eg, a mail attachment containing a virus) from a Time Machine backup?
If you are running 10.6.3 as per your profile, then try either searching these forums for similar problems that have been resolved or post in the Snow Leopard Forums. If you are in fact running an updated version of Lion, then please wait for a high level Guru to answer you. Some of us are apparently not qualified to help sort out anything other than simple problems. They will be along at some stage that fits their qualifications.
Sorry I can't help
You can delete all the backups of items that you normally access via the Finder. From Pondini's FAQ #12, here:
•Locate the backup or item you want to delete via the Timeline or "cascade" of Finder windows.
•If you want to delete all backups of a particular item or items, select it/them in the window.
•Right-click the item (if you're on Leopard, click the "gear" icon in the toolbar) and select either Delete Backup (the entire backup) or Delete all Backups of <item selected> in the small menu that appears.
However I don't know of any way to do this for items that you only access from within an application, such as a Mail message.
Open the document.
1. Move the cursor mouse over the title of the document. You'll see a little triangle appear besides the name.
2. Click it.
3. A menu pops up
4. Select Browse all versions.
Select a version on the right.
Repeat steps 1 through 3
The only possibility you get is to delete that specific version, but if you press the alt/option key that change into Delete all versions.
Anyway as jsd2 pointed out and I was not aware of it is possible also to delete old Time Machine backup, without rendering the entire TM set useless.