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Deliverability Letter

421 OFR004_104

OFR004_104 Too Many Connections

Rate Limiting

Orange slowed or closed the connection because the IP opened too many simultaneous sessions.

Orange ties connection concurrency to reputation. Testing tools or sudden bursts trigger OFR004_104, and repeated hits escalate to longer suspensions.

Severity

WARNING

Provider

Orange

Reference

OFR004_104

Last Reviewed

2025-06-01

How to Fix 421 OFR004_104

Follow these steps to resolve this Orange SMTP error and restore normal delivery.

  • ✓Limit concurrency to a small number of parallel SMTP sessions per IP.
  • ✓Distribute campaigns across a longer send window instead of a single burst.
  • ✓Warm new IPs slowly so Orange can evaluate behaviour.
  • ✓Monitor connection counts per domain in your MTA logs.

Helpful Resources

More Orange SMTP Codes

Keep these related troubleshooting guides handy while addressing 421 OFR004_104.

421 OFR004_105 – OFR004_105 Service Refused
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421 OFR_999 – OFR_999 IP Suspended (2 Hours)
CRITICAL
421 SPF Check Failed – SPF Check Failed
ERROR
421 OFR004_301 – OFR004_301 Suspicious Traffic
WARNING

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