Mail storage and website storage are the same pool, which surprises people.
WHERE IT COUNTS
cPanel's disk usage figure includes files, databases and email combined. A hosting plan filled by email behaves exactly like one filled by a website: uploads fail, databases may go read-only, and mail stops arriving.
WHAT CONSUMES IT
Large attachments, which are the main cause Trash and Junk folders nobody empties Years of mail kept because deleting feels risky Sent items, which are as large as the attachments you sent Mail left on the server by POP3 clients configured to keep copies
CHECKING
cPanel > Email Accounts shows per-mailbox usage. cPanel > Disk Usage shows the mail folder against everything else.
KEEPING IT UNDER CONTROL
Set real quotas rather than unlimited Empty Trash and Junk regularly Archive old mail to your computer rather than keeping everything on the server Use IMAP with sensible folder housekeeping rather than POP3 accumulating copies
IF YOU ARE NEAR THE LIMIT
Clean up first. If mail genuinely needs more space than your plan allows, open a ticket and we will advise.
