Where it accumulates

IMAP keeps everything on the server by default. Sent items with attachments, and shared mailboxes nobody prunes, are the usual bulk.

Practical controls

Worth setting early:

  • Per-mailbox quotas
  • Automatic trash and spam expiry
  • Archiving old mail off-server
  • Alerts before the disk fills

Watch the catch-all

A catch-all address collects every misdirected message and every spam attempt at your domain. It is convenient for a month and a storage problem for a year.