Pro­blem A 40 Gb Gmail account, acces­sed via IMAP with Mail.app. The machine has it har­der and har­der to still work. Old mails do not need to be ins­tantly accessible....

Pro­blem

A 40 Gb Gmail account, acces­sed via IMAP with Mail.app. The machine has it har­der and har­der to still work. Old mails do not need to be ins­tantly accessible.

Solu­tion

Assign old mail a historic label (you can use a fil­ter like before:2010/01/01). Acti­vate Advan­ced IMAP fea­ture lab in Gmail. In the Label tab, uncheck visible in IMAP for the historic label. The machine works again, the new mails are ins­tantly avai­lable and for the old ones, web inter­face at the rescue!

Notes

Mail.app is noto­rious for not allo­wing IMAP unsub­scrip­tion (except on Exchange). For­tu­na­tely, IMAP sub­scrip­tion is a server-side fea­ture. So, if enabled at Gmail-level, all mail clients will com­ply. Even stoo­pid Mail.app.

I still have to check how Mail.app behaves with an already cached fol­der. Does it empty the cache accor­din­gly (this is what is expected)?