Enhanced status code

SMTP error X.1.2

Bad destination system address

Updated Jul 1, 2026

The short answer

Bad destination system address Common cause: Recipient domain does not accept mail or is invalid

Quick fix

Check the domain and its MX/DNS records

This code is written X.1.2 because the reason is the same whether the failure is temporary (a 4 first digit) or permanent (a 5). Read the first digit of your own bounce to know which applies.

How to fix it

Check the domain and its MX/DNS records

Related codes

X.1.0 Other address status X.1.1 Bad destination mailbox address X.1.3 Bad destination mailbox address syntax X.1.4 Destination mailbox address ambiguous X.1.5 Destination address valid X.1.6 Destination mailbox moved, no forwarding address
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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.

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