Knowledge Base

Exceeding mailbox storage quotas

This article discusses what happens when e-mail accounts exceed storage quotas.

What happens when an account exceeds its quota

When you create an e-mail account in cPanel, you have the option of defining a specific storage limit, or quota, for the account. Alternatively, you can specify an unlimited amount of storage space, in which case there is no quota set at all.

For example, if you set a mailbox quota of 100 megabytes, the e-mail account can store up to 100 megabytes of messages. This storage amount includes inbox messages, sent messages, draft messages, message attachments, and any messages in custom folders.

Suppose this account exceeds its storage quota of 100 megabytes. When this happens, the account owner can still send an outgoing message, but receives an error message that the message could not be saved. (When you send a message, it is normally copied to the Sent folder so you have a record of the message. If a mailbox has exceeded its quota, however, the message cannot be saved because there is no more storage space allocated.)

In addition, when an account exceeds its quota, the account owner cannot receive any incoming messages, and senders receive mail delivery failure notifications that resemble the following:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  [email protected]
    Mailbox quota exceeded

Determining an account's disk usage

Most e-mail client applications display current disk usage information so users can determine if their account is approaching (or has already exceeded) its quota.

For example, the Roundcube webmail application displays quota information in the bottom-left corner. The following image shows an account that has exceeded its quota:

Roundcube - quota exceeded

Similarly, the Mozilla Thunderbird e-mail client displays quota information in the bottom-right corner by default. The following image shows an account that has used only 26% of its quota:

Thunderbird - quota usage

If an e-mail account consistently exceeds its quota, there are two options:

  • Increase the account quota, or remove it altogether. You can set quota information in cPanel.
  • Instruct the account owner to regularly review and delete old messages to ensure the account stays within the quota.