SMTP
235 Authentication Successful
The client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session.
When You See This Code
After submitting valid credentials via the AUTH command (LOGIN, PLAIN, or other SASL mechanism). The server has verified your identity and you can now send mail.
How to Fix
No fix needed — authentication succeeded. If you expected this but received a different code, double-check your username, password, and the authentication mechanism.