Recovering space and reducing clutter.
WHAT TO REMOVE
Backup archives you have downloaded Old site copies Deactivated applications Cache directories Log files beyond what you need Old email in Trash and Junk
BEFORE DELETING ANYTHING
Take a backup. Then delete.
WHAT TO BE CAREFUL WITH
Anything you do not recognise. Investigate before deleting.
It may be needed, or it may be a compromise.
FOR MAILBOXES
Empty Trash and Junk Archive old messages locally if you need them Set a mailbox quota so one cannot fill the account
FOR APPLICATIONS YOU NO LONGER USE
Remove the files and the database.
An abandoned application is a security risk, since it is never updated.
THAT IS A COMMON ROUTE OF COMPROMISE
An old installation forgotten in a subdirectory.
HOW OFTEN
Quarterly, or when approaching a limit.
WHAT TO CHECK AFTERWARDS
That the site still works.