Enhanced status code

SMTP error X.7.0

Other or undefined security status

Updated Jul 1, 2026

The short answer

Other or undefined security status Common cause: Unspecified security or policy rejection

Quick fix

Read the full rejection text and check receiver policy

This code is written X.7.0 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

Read the full rejection text and check receiver policy

Related codes

X.7.1 Delivery not authorized X.7.2 Mailing list expansion prohibited X.7.3 Security conversion required but impossible X.7.4 Security features not supported X.7.5 Cryptographic failure X.7.6 Cryptographic algorithm not supported
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