Exact response pattern
550 5.2.3 Message length exceeds administrative limitPermanentGenericContent
What it means
The message is larger than the receiver permits.
Likely causes
- Large attachments.
- Encoded message expansion.
Recommended response
- Reduce message size.
- Use links instead of large attachments.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.