552 5.2.2 Mailbox Full / Over Quota: What to Do on Each Side

A 552 5.2.2 bounce says the recipient's mailbox has no room left. The server knows the address and would deliver, but the storage quota is used up, so the message is refused. It looks alarming because it carries a 5xx code, yet it is the one hard bounce that routinely fixes itself: the recipient deletes something, and the next message arrives. This page covers both sides, reaching someone whose inbox is full and clearing your own, plus the look-alike error that is actually about message size.

Quick answer

If someone else's mailbox is full, you cannot fix it; contact them another way and resend in a day or two. If your own mailbox is full, empty Trash and Spam, delete the largest attachments, and move old mail out over IMAP. On OquMail each mailbox has 5 GB; the Storage page in the admin area shows how much each mailbox uses.

The common wordings

• "552 5.2.2 Mailbox full" or "552 5.2.2 <address>: Recipient address rejected: Quota exceeded" from most hosted providers.
• Gmail: "552-5.2.2 The email account that you tried to reach is over quota."
• Microsoft 365: "554 5.2.2 mailbox full; STOREDRV.Deliver.Exception:QuotaExceededException".
• Not the same thing: "552 5.3.4 Message size exceeds fixed maximum message size". That one is about your message being too large, not the recipient's storage. Send the file as a link instead; see sending large files.

If the recipient is full

1. Do not resend immediately. Repeated attempts bounce the same way and add noise to your delivery log.
2. Reach the person by phone, chat or a colleague's address and tell them their inbox is full. Most people do not know until someone says so.
3. Resend after a day or two. If it bounces again after a week, treat the address as dead and stop sending.
4. For newsletters and sequences, pause the address rather than removing it; it usually comes back.

If your mailbox is full

1. Check how much space is used. On OquMail an admin opens Storage in the admin area, which lists every mailbox with its used space out of 5 GB.
2. Empty Trash and Spam first. Deleted mail still counts until the folder is emptied.
3. Sort the inbox and Sent folder by size and delete or save the large attachments. Ten messages with 20 MB attachments are 200 MB.
4. Archive old mail out of the mailbox. A desktop app such as Thunderbird can move whole years into a local folder; our backup over IMAP guide shows how.
5. If the mailbox fills again within weeks, the inflow is the problem: unsubscribe from the heavy senders, and ask customers to share files by link.

Keep it from happening again

Set a rule to delete large automatic messages (system reports, backup notices) after 30 days, keep Sent lean by not attaching files you also store elsewhere, and check the storage bar once a month. The storage quota guide has a routine that takes five minutes.

Common questions

Will the mail that bounced be delivered once there is space?

No. The sender received a bounce and the message is gone. Ask them to resend after you have cleared space.

Does a full mailbox stop me from sending?

On most providers, including OquMail, sending still works while receiving fails, but sent copies cannot be stored. Clear space first so your Sent folder keeps a record.

Can I buy more space?

On OquMail, mailboxes are 5 GB each and extra mailboxes are available on request, so spreading archives across a second mailbox is the usual answer rather than a bigger single box.