Sometimes, you are unable to send/receive emails and receive errors like "domain size limit has been exceeded". This error clearly indicates that your mail domain quota has exceeded the allotted limit. To fix this, you can clear out unwanted emails from mailboxes to free up some space but you will need to identify which mailboxes are occupying more disk space.
Here's an article you should refer to check disk usage of mail domain and individual accounts. If you wish to increase the mail domain disk space quota, follow these steps.
- Login to SmarterMail with admin user.
- From the left navigation bar, click on Settings icon.
- Expand Defaults and click on Domain Defaults in the left window pane.
- Click on the Limits tab and set the Disk Space Quota. Click on Save button to save the changes.