ONLINE
Deliverability Letter

450 4.7.1

SFR_IN_106 Too Many Messages per Recipient

Rate Limiting

The IP sent too many messages to the same recipient or group within a short interval.

SFR monitors per-user frequency. Automated testing or transactional retries can look like abuse and trigger SFR_IN_106.

Severity

WARNING

Provider

SFR

Reference

SFR_IN_106

Last Reviewed

2025-06-01

How to Fix 450 4.7.1

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

  • Implement per-user frequency caps for SFR addresses.
  • Stagger transactional retries instead of retrying instantly.
  • Group low-importance alerts into digests rather than multiple sends.
  • Educate support teams to avoid repeated resends to the same mailbox.

Still experiencing SFR delivery issues?

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