5.2.2

Enhanced Status Code 5.2.2: Mailbox Full - Over Quota

Temporary failure Medium severity Mailbox RFC 3463
What it means

Enhanced Status Code 5.2.2 means “Mailbox Full - Over Quota.” The recipient mailbox has exceeded its storage quota and cannot accept new messages. This is one of the most common soft bounce codes. The email may be delivered if the recipient deletes messages to free up space.

At a glance
Code5.2.2
Bounce typeSoft (temporary)
SeverityMedium
CategoryMailbox
What to doQueued and retried automatically
StandardRFC 3463
What it looks like in your mail logs 
host example.com[192.0.2.55] said: 552 5.2.2 <user@example.com>: Recipient address rejected: Mailbox full (in reply to RCPT TO command)

What does 5.2.2 mean?

Enhanced status code 5.2.2 (or 4.2.2 for the temporary variant) is one of the most frequently encountered bounce codes. It means the recipient's mailbox has reached its storage limit and cannot accept any more messages until the recipient deletes existing emails to free up space.

Despite starting with 5 (permanent), many email systems treat 5.2.2 as a soft bounce because the condition can be temporary. Gmail provides 15GB of shared storage across Gmail and Drive, Microsoft 365 provides 50GB for business accounts. When these limits are reached, incoming email bounces with this code.

A chronically full mailbox often indicates an abandoned or rarely-checked account. If the same address bounces with 5.2.2 consistently over several days, suppress it from your active list. Users who come back and free up space can re-subscribe.

How 5.2.2 plays out

Your server attempts delivery
The recipient defers with a temporary 5.2.2 reply
Your server queues the message and retries on a back-off schedule
It delivers on a later attempt, or becomes a hard bounce if it keeps failing

Where 5.2.2 sits: soft vs hard bounce

Soft bounce (4xx) Hard bounce (5xx)
NatureTemporaryPermanent
SMTP class4xx5xx
What to doLet it retrySuppress the address
Recoverable?OftenNo
5.2.2 is✓ this code

Common causes of 5.2.2

  • Recipient has exceeded their mailbox storage quota
  • Mailbox is abandoned and has filled up over time
  • Recipient receives high volume of email without archiving or deleting
  • Organization has set restrictive storage limits
  • Large attachments consuming the available quota

How to fix 5.2.2

  • Retry delivery after 24-48 hours - the recipient may clear space
  • Suppress the address after 3-5 consecutive bounces over multiple days
  • Alert the recipient through another channel if possible
  • Implement soft bounce handling in your ESP to auto-suppress after repeated failures

Frequently asked questions

What does bounce code 5.2.2 "mailbox full" mean?
Bounce code 5.2.2 means the recipient's mailbox has exceeded its storage quota and cannot accept new messages. The email server rejected your message because there is no remaining space in the recipient's account. This commonly occurs with personal email accounts (Gmail, iCloud, Yahoo) where storage is shared across services like cloud drive and photos, and with corporate accounts that have administrative mailbox size limits.
Is a mailbox full bounce a hard bounce or soft bounce?
A mailbox full bounce is typically classified as a soft bounce when returned as a 4.2.2 (temporary) code, meaning the server will retry delivery. However, when returned as 5.2.2 (permanent), it is treated as a hard bounce. Most email service providers retry delivery for 24 to 72 hours before giving up. If the mailbox remains full after multiple retries, suppress the address temporarily and reattempt after 30 days.
How long does it take for a full mailbox to accept email again?
Delivery resumes as soon as the recipient frees up storage space; there is no fixed waiting period. Mail servers typically retry delivery for 24 to 72 hours (Gmail retries for about 48 hours, Microsoft Exchange Online for 24 hours). If the recipient clears space within that retry window, queued messages will be delivered automatically. Over 50% of temporarily bounced full-mailbox addresses become active again within a few months, but persistently full inboxes often indicate abandoned accounts.
How do I fix the 5.2.2 over quota error?
If you are the recipient, delete old emails (especially those with large attachments), empty your Trash and Spam folders, and manage other data that shares your storage quota (Google Drive, iCloud Drive, OneDrive). If you are the sender, there is nothing you can do except wait for the recipient to free space or contact them through another channel. For administrators on Microsoft Exchange or Google Workspace, you can increase the mailbox quota for affected users.

Related bounce codes

422 Recipient Mailbox Storage Exceeded 452 Insufficient System Storage 4.2.2 Mailbox Full - Temporary 5.2.1 Mailbox Disabled or Not Accepting Messages

Sources & further reading

RFC 3463 · The standard that defines this reply code Google Workspace, Fix bounced or rejected emails · Gmail help section "The recipient's inbox is out of storage space".
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← All bounce codes