What 550 5.2.2 Means
The recipient's mailbox has exceeded its storage quota. Per RFC 3463 §3.2, status code 5.2.2 is 'mailbox full.' Gmail returns this when the recipient — typically a Workspace user with a finite mailbox size — is at their cap and can't receive new messages.
Gmail and Workspace recipients where the user has hit their per-mailbox quota. Less common at consumer Gmail (15 GB is rarely hit by passive users) but common at smaller Workspace allocations.
Recipient hasn't cleaned out their inbox. Often elderly accounts that accumulate years of mail. Or shared mailboxes (info@, sales@) that get high volume and aren't actively maintained.
How to Fix 550 5.2.2
- 1
Wait and retry briefly
Some users clean out their inbox sporadically and the quota frees up. Most sending platforms retry 5.2.2 for a few cycles before giving up. If the address comes back deliverable in a few days, you're fine.
- 2
If persistent — suppress the address
If 5.2.2 persists for weeks, the recipient isn't going to fix their quota. Mark the address as soft-suppressed in your CRM (eligible for re-validation after 30-90 days). Don't keep retrying — each retry adds to your sender's bad-delivery statistics.
- 3
Watch for the 'role account' pattern
Role accounts (info@, sales@, contact@) commonly hit 5.2.2 because they receive high volume and rarely get cleaned. These are also low-engagement prospects (typically routed to a generic queue). Consider excluding role accounts from cold email by default.
- 4
Find an alternate contact at the same organization
If the over-quota prospect is at a target organization, find a different individual contact via LinkedIn or company directory. Don't keep retrying the same dead address.
References
550 5.2.2 in the Cold Email Context
5.2.2 is mostly noise for cold email — it's a recipient-side problem you can't fix. The cold-email-specific takeaway: chronically-over-quota addresses are inactive accounts. If the prospect can't even free up their inbox, they're not actively reading mail, and they're a poor prospect. ColdRelay's bounce classification tracks repeat-5.2.2 addresses so they're auto-excluded from future campaigns until they pass a re-validation cycle (typically 90 days).
Frequently Asked Questions
How is 5.2.2 different from 452?
452 is transient (4xx, retry). 5.2.2 is permanent (5xx, give up). Some receivers escalate from 452 to 5.2.2 after sustained retries fail. The cause is the same — recipient over quota — but the severity changes based on receiver policy.
Will my message be delivered when the recipient frees space?
No — by the time they free space, your message has been bounced. They need to receive the mail in real-time. If you re-send later, the new message may deliver if quota has been freed.
Does 5.2.2 affect my sender reputation?
Slightly. Receivers track non-delivery rates; high 5.2.2 rates signal poor list hygiene. The impact is small if your overall bounce rate stays under 2%.
Should I auto-suppress 5.2.2 addresses?
Yes, with re-validation. A first 5.2.2 may resolve in days. After 2-3 consecutive 5.2.2 events, soft-suppress the address. Re-validate after 90 days to see if quota has been freed.