The mailbox size (quota) determines the maximum number of emails and attachments that an email account can store. All folders within the mailbox count towards the quota: in addition to the Inbox, this includes the Sent, Deleted (Bin) and Spam folders.

How can I check my usage?

• In cPanel: in the ‘Email’ section, open the ‘Email Accounts’ menu item. The used and allocated storage space is displayed next to each email account.
• In Webmail: on the Roundcube Settings > Folders page, clicking on a folder displays its size, whilst the total usage is shown in the bottom left-hand corner.

What happens when it’s full?

If a mailbox reaches its quota, the server will not accept any new incoming emails but will return them to the sender with an error message such as ‘mailbox full’ or ‘quota exceeded’. The sender is therefore notified that their email has not been delivered, but these emails will not reach you even after space has been freed up; they must be resent. The article explaining Exim status codes provides information on interpreting these error messages.

How can you free up space?

1. Empty the Bin and the Spam folder. These often take up several hundred megabytes and count towards your quota.
2. Find large emails. In Roundcube, you can quickly locate large attachments by sorting your email list by size. The ‘Email Disk Usage’ menu item in cPanel shows the size per folder, and allows you to delete, for example, emails older than one year or an entire folder in a single step.
3. Archive your old emails on your own computer. In an email client (such as Thunderbird or Outlook), create a local folder and move your old emails there; this will remove them from the server. When doing so, please ensure you perform a backup of your computer as well.
4. Links instead of attachments. It is better to send large files via a download link; this is covered in the article on sending large files by email.

How can I increase my quota?

On cPanel hosting, you can adjust the quota on the Email Accounts page by clicking the ‘Manage’ button next to the mailbox, within the limits of your plan’s hosting allowance. If your plan’s hosting allowance is insufficient, please choose a larger plan: you can select from several sizes amongst our email hosting plans, and our support team will be happy to assist you with switching plans. Our blog post provides detailed information on increasing your mailbox quota and optimising hosting.

POP3 or IMAP?

When using POP3, your email client may delete messages from the server after downloading them, so your mailbox rarely fills up; however, the messages will only be stored on that particular device. When using IMAP, messages remain on the server and are accessible from all devices, so it is advisable to check your storage usage from time to time.