3-digit reply code Success

SMTP error 251

User not local; will forward.

Updated Jul 1, 2026

The short answer

User not local; will forward. Common cause: The recipient is not hosted here, so the server will relay it onward.

Quick fix

A normal relay action — nothing to fix.

2 - Success. Not an error - the server accepted or completed the action.

How to fix it

A normal relay action — nothing to fix.

Related codes

211 System status or help reply. 214 Help reply. 220 Service ready. 221 Service closing transmission channel. 235 Authentication successful. 250 Requested action completed.
All SMTP error codes
Ready when you are

Most rejections come back to sender reputation.

Blocklists, auth failures, and policy blocks are what warmup prevents. Warm up your domain so your mail is trusted before you hit send.

Start 7-day free trial Book a demo
7-day free trialNo credit cardCancel anytime