SMTP error codes:
Complete lists, error description and solutions

What is an SMTP error code?

SMTP, or Simple Mail Transfer Protocol, is the standard protocol for sending and receiving email messages. SMTP error codes are three-digit numerical codes generated by email servers to communicate the status of email deliveries or to report issues encountered during the email transmission process.

These error codes play a crucial role in diagnosing and troubleshooting email-related problems. Below, you'll find a comprehensive list of SMTP error codes, along with detailed descriptions and recommended solutions to resolve them.

List of SMTP error codes

Click on each error code to learn more about its description, common root causes, and suggested solutions:
We’re here to change the way you fire notifications!
There’s a smarter way to manage your notifications without using valuable engineering time.
Don’t wait to have million users to deliver meaningful in-app experience.
Launch your app with best-in-class notification inbox with Fyno.
Request access
Black Arrow