Exact response pattern
550 5.4.1 Recipient address rejected: Access deniedPermanentGenericRouting
What it means
The receiving gateway rejects delivery to the addressed route or tenant.
Likely causes
- Wrong tenant or routing target.
- Recipient domain not accepted by the gateway.
- Directory-based edge blocking.
Recommended response
- Verify MX records and tenant routing.
- Confirm the recipient exists in the destination organization.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.