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Deliverability Letter

450 4.7.1

LPN027_503 Service Refused

Service Refused

Laposte temporarily refused the connection after seeing too many errors or complaints.

LPN027_503 is Laposte’s generic throttle when reputation drops. It normally clears after a few hours if you slow delivery and clean your list.

Severity

WARNING

Provider

Laposte.net

Reference

LPN027_503

Last Reviewed

2025-06-01

How to Fix 450 4.7.1

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

  • Reduce concurrent SMTP connections to no more than two per IP.
  • Respect Laposte’s limit of ~100 messages per connection.
  • Pause unengaged French recipients and remove obvious spam traps.
  • Check the Signal Spam feedback loop for complaint spikes.

Still experiencing Laposte.net delivery issues?

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