Bounce "552 5.2.2": the mailbox is full

What it means

Your email came back with a message such as:

552 5.2.2 The email account that you tried to reach is over quota

Other wordings include Mailbox full, Quota exceeded or Insufficient storage. Sometimes the code starts with 452 4.2.2 instead: that is the temporary version, and your server will keep trying for a while.

It means the recipient's mailbox has no space left. The address exists, but the server cannot store anything new until the person deletes some emails or buys more space.

Why it matters

• Your setup is not at fault: SPF, DKIM and DMARC have nothing to do with this error.
• The person will not see your email until they free up space.
• An address that stays full for weeks is usually abandoned. Nobody reads it, and some providers later turn old abandoned mailboxes into spam traps.

How to check

• Read the bounce: it names the full mailbox and the server that refused it.
• Look at its history: in your newsletter tool, check whether the same address bounced as "full" in earlier campaigns.
• Check large attachments: a very big attachment can be refused by a nearly full mailbox while small emails still get through.

How to fix it

1. For one important contact: reach them another way (phone, another address) and tell them their mailbox is full. Once they clean it, resend your email.
2. Send smaller emails: share large files with a download link instead of an attachment.
3. For mailing lists: let your tool handle it. Most treat "mailbox full" as a soft bounce and retry on the next campaign.
4. Remove addresses that stay full. If an address bounces as full on three or more campaigns in a row, or for more than a month, remove it or move it to an inactive segment.
5. Do not resend in a loop. Sending the same email again and again to a full mailbox will not help and can look like spam.

If the full mailbox is yours

If people tell you their emails to your address bounce with 5.2.2, your own mailbox is full. Delete old emails with big attachments, empty the trash and spam folders, or upgrade your storage plan with your provider. With Google accounts, storage is shared with Google Drive and Photos, so large files there count too.

Check that it is fixed

For a contact: once they confirm they freed space, send one short email and check that no bounce comes back. For a list: watch your next campaign reports and make sure repeat "mailbox full" addresses are no longer being sent to.