Programming Tutorials

  If you are reading this, you are likely staring at a bounce message that looks something like this:   550 5.7.26 This message does not have authentication information or fails to pass authentication checks. Since Google and Yahoo implemented strict sender guidelines in early 2024, the "wild west" era of email is officially over. Sending emails from a custom domain without rigorous DNS authentication now guarantees rejection or the spam folder. For developers and system administrators using Namecheap, this transition presents specific challenges. Namecheap's "Advanced DNS" panel has idiosyncratic behaviors regarding hostnames and record conflicts that often result in silent failures, even when the configuration looks correct to the naked eye. This guide details the root cause of these failures and provides the exact, copy-paste configuration required to achieve 100% deliverability compliance. The Engineering Behind the 550 Error To fix the problem, we must unde...