10-11-2026, 12:25 PM
Mailbox quota limits how much email one account can store. Increase it when more storage is needed, but check server disk space and the domain allowance first.
Tested: aaPanel Free Edition 8.0.6 with Mail Server 7.4.1. We changed [email protected] from 1 GB to 2 GB, verified the mailbox row, and restored 1 GB afterward. The password and enabled status were unchanged.
1. Check the current allowance
Open Mail Server → Mailboxes. Find the full email address, using Search Email if needed. Read its Quota column: our row changed from 0.00 B/1.00 GB to 0.00 B/2.00 GB. The first number is reported usage; the second is the limit. A rounded zero does not prove that the mailbox contains no messages.
Also inspect Mail Domain for the domain quota and default mailbox size. These are separate settings. Raising one mailbox limit does not create additional disk capacity. Check Home disk usage or run
on Ubuntu. Our lab had 29 GB available during this test.
2. Edit one mailbox
1. In the correct mailbox row, click Edit.
2. Verify the dialog says Edit Mailbox and shows the intended Email Address.
3. Keep Quota limit enabled.
4. Enter the new amount in Quota, then confirm the adjacent unit. We entered 2 with GB selected.
5. Keep the existing Name and User type unless those also need an intentional change.
6. Leave Email Password empty. The dialog explicitly says an empty value leaves the password unchanged.
7. Click Confirm once and wait for the mailbox list to update.
3. Verify the result
Check the same row again. Its allowance should now show the requested value and Status should remain enabled. If the old value remains, reopen Edit and check whether the setting actually saved before trying again. Test normal mailbox access through webmail.
![[Image: mail-quota-branded-20261011.png]](https://adminsforum.com/uploads/tutorials/mail-quota-branded-20261011.png)
Screenshot: the actual lab row after the successful 2 GB change. The lab was subsequently returned to 1 GB.
4. If the mailbox is already full
Increasing the allowance can help only when the underlying server has space. Review large attachments, Sent, Junk and Trash. Export or back up messages you need before permanent cleanup. Deleting a mailbox is not a quota adjustment: it can remove the account and its mail.
Do not reduce the allowance below current usage as a routine cleanup method. First reduce stored mail or choose a sufficient limit, then verify delivery with a new message.
5. Check quota notifications
Under Mail Server → Other Settings → Common settings, our panel showed Send email when quota exceeded enabled. Check your own setting and test the notification separately; we did not deliberately fill this mailbox or verify an over-quota alert.
Related: Create a user mailbox
Tested: aaPanel Free Edition 8.0.6 with Mail Server 7.4.1. We changed [email protected] from 1 GB to 2 GB, verified the mailbox row, and restored 1 GB afterward. The password and enabled status were unchanged.
1. Check the current allowance
Open Mail Server → Mailboxes. Find the full email address, using Search Email if needed. Read its Quota column: our row changed from 0.00 B/1.00 GB to 0.00 B/2.00 GB. The first number is reported usage; the second is the limit. A rounded zero does not prove that the mailbox contains no messages.
Also inspect Mail Domain for the domain quota and default mailbox size. These are separate settings. Raising one mailbox limit does not create additional disk capacity. Check Home disk usage or run
Code:
df -h /2. Edit one mailbox
1. In the correct mailbox row, click Edit.
2. Verify the dialog says Edit Mailbox and shows the intended Email Address.
3. Keep Quota limit enabled.
4. Enter the new amount in Quota, then confirm the adjacent unit. We entered 2 with GB selected.
5. Keep the existing Name and User type unless those also need an intentional change.
6. Leave Email Password empty. The dialog explicitly says an empty value leaves the password unchanged.
7. Click Confirm once and wait for the mailbox list to update.
3. Verify the result
Check the same row again. Its allowance should now show the requested value and Status should remain enabled. If the old value remains, reopen Edit and check whether the setting actually saved before trying again. Test normal mailbox access through webmail.
Screenshot: the actual lab row after the successful 2 GB change. The lab was subsequently returned to 1 GB.
4. If the mailbox is already full
Increasing the allowance can help only when the underlying server has space. Review large attachments, Sent, Junk and Trash. Export or back up messages you need before permanent cleanup. Deleting a mailbox is not a quota adjustment: it can remove the account and its mail.
Do not reduce the allowance below current usage as a routine cleanup method. First reduce stored mail or choose a sufficient limit, then verify delivery with a new message.
5. Check quota notifications
Under Mail Server → Other Settings → Common settings, our panel showed Send email when quota exceeded enabled. Check your own setting and test the notification separately; we did not deliberately fill this mailbox or verify an over-quota alert.
Related: Create a user mailbox