SMTP 235 Authentication Successful vs 452 Insufficient Storage
SMTP 235 (Authentication Successful) is a 2xx Positive Completion response, while 452 (Insufficient Storage) is a 4xx Transient Negative response. 235 indicates that the client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session. In contrast, 452 means that the requested action was not taken because the server has insufficient system storage. The server cannot accept more mail until storage is freed.
Description
The client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session.
When You See It
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.
Description
The requested action was not taken because the server has insufficient system storage. The server cannot accept more mail until storage is freed.
When You See It
When the mail server's disk is full or the recipient's mailbox has exceeded its storage quota. The server cannot store additional messages.
How to Fix
If you are the sender, retry later after the recipient frees up space. If you manage the server, clear disk space, increase quotas, or archive old messages.
Key Differences
235 is a 2xx Positive Completion response, while 452 is a 4xx Transient Negative response.
SMTP 235: The client has been successfully authenticated using the AUTH command. The server will now accept mail commands from this authenticated session.
SMTP 452: The requested action was not taken because the server has insufficient system storage. The server cannot accept more mail until storage is freed.
You encounter 235 when 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.
You encounter 452 when when the mail server's disk is full or the recipient's mailbox has exceeded its storage quota. The server cannot store additional messages.
When to Use Which
For 235 (Authentication Successful): No fix needed — authentication succeeded. If you expected this but received a different code, double-check your username, password, and the authentication mechanism. For 452 (Insufficient Storage): If you are the sender, retry later after the recipient frees up space. If you manage the server, clear disk space, increase quotas, or archive old messages.