Managing email storage quotas in cPanel
Set and manage email storage quotas for mailboxes. What happens when a mailbox is full, how to increase quota, and how to clean up old mail to free space.
UnderHost NOC
Network Operations
On this page
A mail quota is the maximum disk space a mailbox can use. When a mailbox hits its quota, new mail cannot be delivered. Senders receive a bounce message. Understanding and managing quotas keeps your email working reliably.
What is a mail quota?
Each email account on your cPanel hosting has a storage quota measured in MB or GB. This is the space on the server used to store email messages, attachments, and mail folder data. It counts against your overall hosting disk space.
Check mailbox usage
- Log in to cPanel
- Go to Email → Email Accounts
- Each account shows its current usage and quota in the list
The usage bar fills as storage is used. A full bar means the mailbox has reached its quota limit.
Change a mailbox quota
- In Email Accounts, click the three-dot menu (⋮) or Manage next to the mailbox
- Click Manage → Storage Used
- Enter a new quota in MB or check Unlimited
- Click Update Quota
Setting quota to "Unlimited" doesn't grant infinite storage-it means the mailbox can use however much of your hosting account's total disk space is available. If your hosting disk is full, mail won't be delivered regardless of quota settings.
What happens when a mailbox is full
When a mailbox reaches its quota:
- New incoming mail is bounced back to the sender with a "Mailbox Full" or "User over quota" error
- The webmail interface may show errors when trying to save drafts or receive mail
- Email clients may fail to sync new messages
The fix: increase the quota, or delete old mail from the mailbox.
Free up mailbox space
- Delete large attachments: Sort inbox by size in webmail (Roundcube) to find emails with large attachments and delete or download them
- Empty Trash and Spam: Go to Trash and Spam folders in webmail and empty them-deleted messages stay in Trash until emptied
- Archive old mail: In Outlook or Thunderbird, use the archive feature to move old messages off the server to local storage
- Reduce POP3 retention: If using POP3, configure your email client to delete messages from the server after downloading-this prevents accumulation on the server
Related: How to set up email accounts in cPanel | How to access webmail (Roundcube) | Configuring email in Outlook, Thunderbird, and Apple Mail | Email aliases and multiple addresses in cPanel
Need email hosting?
UnderHost shared and managed hosting include mailbox, webmail, DNS, SPF/DKIM, and email support for your domain.
