450 4.2.1
450 4.2.1 Mailbox Inactive
The recipient’s Laposte mailbox is temporarily disabled or inactive.
Dormant mailboxes are common on older Laposte accounts. Treat the bounce as soft unless it occurs repeatedly over several weeks.
Severity
WARNING
Provider
Laposte.net
Last Reviewed
2025-06-01
How to Fix 450 4.2.1
Follow these steps to resolve this Laposte.net SMTP error and restore normal delivery.
- ✓Retry in subsequent campaigns before suppressing the address.
- ✓Run a win-back campaign targeting Laposte recipients who have not opened recently.
- ✓Flag the contact for sales or customer success outreach if the relationship is strategic.
- ✓Stop after 3–4 consecutive failures to avoid reputation damage.
Helpful Resources
More Laposte.net SMTP Codes
Keep these related troubleshooting guides handy while addressing 450 4.2.1.
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