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Error code

SMTP 550 5.1.1 — Recipient address rejected

The recipient address does not exist or is not recognized by the remote mail domain.

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SMTP 550 5.1.1 — Recipient address rejected

Domain: EmailPriority: High

What does this error mean?

The recipient address does not exist or is not recognized by the remote mail domain.

Likely causes

  • The recipient address is misspelled
  • The mailbox was removed
  • The expected alias is missing

Checks and resolution

  1. Verify the recipient address.
  2. Check the directory or mailbox configuration.
  3. Verify the domain MX records and retry with a known valid recipient.
Precaution: Avoid repeatedly retrying delivery to an address confirmed as invalid.

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Quick diagnostic.

To diagnose SMTP 550 5.1.1 in the Email domain, start with the following check: Check address. Then check the result against this probable cause: incorrect address. Save context and time of appearance to compare behavior before and after correction. Priority level indicated: High.

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