Microsoft mail servers 550 5.2.2
Quota or rate limit
The provider is slowing or deferring traffic. Retrying can work, but repeated deferrals usually mean volume, reputation, or recipient engagement needs review.
Do not assume Exchange 5.2.2 always means recipient mailbox full.
Decision
Do not retry unchanged. Fix the sender setup first.
Confidence: medium. Recipient validity: unknown.
Match this reply
- SMTP stage
- Any SMTP stage
- Endpoint
- Any endpoint
quotasubmissionlimitUse tools
Start here
- 1
Read the full SMTP diagnostic text, not only the numeric reply code.
- 2
Identify the provider, SMTP stage, and any provider token before deciding whether to retry or suppress.
Confirm the cause
- Review recent sending volume, bounce rate, complaint rate, and list hygiene for this provider.
- Confirm SPF, DKIM, and DMARC alignment so reputation problems are not made worse by authentication failures.
- Resume with lower provider-specific volume only after deferrals stop or the provider accepts test mail.
App handling
- Treat this as a sender setup incident, not a bad recipient.
- Hold similar mail for the same sender domain or provider until the fix is verified.
- Retry after a fresh single-recipient test succeeds.
Avoid
- Do not retry unchanged in a loop.
- Do not suppress the recipient unless the text explicitly says the mailbox is invalid.
- Do not treat a permanent SMTP code as proof that the address is bad; policy and routing failures can also be permanent.
Common causes
- Volume increased faster than the provider trusts for this sender.
- Recent bounces, complaints, or low engagement damaged sender reputation.
- The provider applied a traffic, content, or sender policy to protect recipients.
Developer details
Fields to log
raw SMTP replyremote MX or hostSMTP stagereply codeenhanced codeprovidermatched rule idrecipientsending domaindecisiontimestampprovider retry countsend volume windowbounce rate
Classifier evidence
- Specific cause
- exchange contextual 5 2 2
- Evidence
- official