Storing Less Mail Locally With Thunderbird for IMAP

Choose to keep only the most recent emails on your computer

Thunderbird
Thunderbird

How many copies of every email in every folder do you need? It's good to have them all on the IMAP email server, of course, in backup copies at the email service, and locally in an email program. However, it may not be necessary for Mozilla Thunderbird, which you use now and then for a particular purpose, to feverishly start downloading all your new mail whenever you start it and to store gigabytes of old mail, too.

Whether you use Mozilla Thunderbird only sporadically or just want to preserve disk space on a mobile machine, you can set it up to store only the most recent messages on your computer. What counts as recent is mostly up to you.

Leave Last Year's Emails on the Server

To set up Mozilla Thunderbird to keep only a certain amount of mail locally for fast search in an IMAP account:

  1. Select Tools Account Settings from the menu in Mozilla Thunderbird.
  2. Go to the Synchronization & Storage category for the desired account.
  3. Select Synchronize the most recent under Disk Space.
  4. Choose the time for which you want Mozilla Thunderbird to keep a local copy of your emails. Select 6 Months, for example, to have six months of email available offline for speedy search.
  5. Click OK.

Older messages still appear in the IMAP account's folders. It is just the message text that is not kept on your computer for faster access. If you delete such an older message, it is deleted on the IMAP server, too.

To search all mail—including mail only available in full on the server—select Edit > Find > Search Messages… from the menu and check Run a search on server.