Each mailbox has a quota: the most it’s allowed to store. All mailboxes together share your account’s 3GB with the website and databases.
Checking usage
E-mail Manager then E-mail Accounts lists each account’s usage against its quota. E-mail Manager then E-mail Usage shows what’s using the space.
When a mailbox is full
New incoming mail is rejected, and senders get a bounce such as “mailbox full” or “quota exceeded”. Nothing arrives until space is freed.
Raising a quota
- Open E-mail Manager then E-mail Accounts.
- Edit the account’s settings.
- Increase the quota and save.
Only raise it if the account itself has room: a large quota on a nearly full hosting account just moves the problem.
Stopping it filling up again
- Empty Trash and Junk. Deleted mail stays there, still counted.
- Remove old attachments. A few large attachments often outweigh thousands of messages.
- Archive locally. In your mail app, move older years into a local folder (“On My Mac”, Outlook’s local data file, Thunderbird’s Local Folders). They stay on your computer and leave the server.
- Check the Sent folder. It grows quietly.
POP3 and space
POP3 apps download mail and usually delete it from the server, which keeps usage low but means messages only exist on one device. IMAP keeps everything on the server. IMAP vs POP3: which should I use?