SMTP code guide

SMTP 552 5.2.2: provider meanings and fixes

SMTP 552 5.2.2 can mean recipient mailbox quota, storage, or account capacity issue. Compare Gmail and Apple handling before retrying or suppressing.

Quick summary

Primary code
552 5.2.2
Provider coverage
Gmail, Apple
Primary action
Do not retry unchanged

How to handle 552 5.2.2

Start by matching the provider wording, then use the matching section below. The same SMTP code can call for different actions depending on whether it points to recipient validity, routing, sender setup, or policy.

Gmail 552 5.2.2

Recipient issue

Do not retry unchanged

The provider is rejecting the mailbox or account. Only treat it as invalid when the provider-specific text, endpoint, and stage all point to recipient validation.

Recipient is probably real; do not suppress merely because the mailbox is full.

Decision

Review the full SMTP reply before retrying.

Confidence: high. Recipient validity: valid.

Match this reply

SMTP stage
End of DATA
Endpoint
Inbound MX
over quotastoragemailbox full

Start here

  1. 1

    Confirm the recipient address and domain are spelled correctly.

  2. 2

    Suppress the recipient only when the provider-specific evidence says the mailbox is invalid.

Confirm the cause

  1. Validate the recipient address and domain before suppressing it.
  2. Check whether the mailbox, alias, group, or contact exists and can receive external mail.
  3. Keep the full SMTP reply with the contact record so support can distinguish invalid addresses from policy blocks.

App handling

  • Route to manual review or a conservative fallback classification.
  • Do not suppress the recipient from this rule unless a later bounce gives stronger recipient evidence.
  • Limit automated retries until the provider-specific cause is understood.

Avoid

  • Do not decide from the SMTP code alone.
  • Do not suppress unless the provider-specific evidence points to an invalid recipient.
  • Do not retry high-volume traffic before you understand the diagnostic text.
Common causes
  • The address is misspelled, deleted, disabled, or not mail-enabled.
  • The recipient domain accepts mail, but the specific mailbox cannot receive this message.
  • An alias, distribution group, or forwarded address no longer maps to a valid mailbox.
Developer details
Fields to log
raw SMTP replyremote MX or hostSMTP stagereply codeenhanced codeprovidermatched rule idrecipientsending domaindecisiontimestampenvelope recipientcontact id
Classifier evidence
Specific cause
mailbox over quota
Evidence
official
support.google.com source 1

Apple 552 5.2.2

Recipient issue

Do not retry unchanged

The provider is rejecting the mailbox or account. Only treat it as invalid when the provider-specific text, endpoint, and stage all point to recipient validation.

Do not suppress. The recipient is likely valid.

Decision

Review the full SMTP reply before retrying.

Confidence: medium. Recipient validity: valid.

Match this reply

SMTP stage
End of DATA
Endpoint
Inbound MX
over quota

Start here

  1. 1

    Confirm the recipient address and domain are spelled correctly.

  2. 2

    Suppress the recipient only when the provider-specific evidence says the mailbox is invalid.

Confirm the cause

  1. Validate the recipient address and domain before suppressing it.
  2. Check whether the mailbox, alias, group, or contact exists and can receive external mail.
  3. Keep the full SMTP reply with the contact record so support can distinguish invalid addresses from policy blocks.

App handling

  • Route to manual review or a conservative fallback classification.
  • Do not suppress the recipient from this rule unless a later bounce gives stronger recipient evidence.
  • Limit automated retries until the provider-specific cause is understood.

Avoid

  • Do not decide from the SMTP code alone.
  • Do not suppress unless the provider-specific evidence points to an invalid recipient.
  • Do not retry high-volume traffic before you understand the diagnostic text.
Common causes
  • The address is misspelled, deleted, disabled, or not mail-enabled.
  • The recipient domain accepts mail, but the specific mailbox cannot receive this message.
  • An alias, distribution group, or forwarded address no longer maps to a valid mailbox.
Developer details
Fields to log
raw SMTP replyremote MX or hostSMTP stagereply codeenhanced codeprovidermatched rule idrecipientsending domaindecisiontimestampenvelope recipientcontact id
Classifier evidence
Specific cause
mailbox over quota
Evidence
observed
support.apple.com source 1

Not sure this is the right match?

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