SMTP 221 Closing Connection vs 452 Insufficient Storage
SMTP 221 (Closing Connection) is a 2xx Positive Completion response, while 452 (Insufficient Storage) is a 4xx Transient Negative response. 221 indicates that the server is closing the transmission channel. This is the normal response to the QUIT command, indicating a graceful end to the SMTP 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.
Beschreibung
The server is closing the transmission channel. This is the normal response to the QUIT command, indicating a graceful end to the SMTP session.
Wann Sie es sehen
After sending the QUIT command at the end of a mail session. The server acknowledges the disconnect and the TCP connection will be closed.
Wie man es behebt
No fix needed — this is the expected response when ending an SMTP session. If you see this unexpectedly, the server may be shutting down or timing out idle connections.
Beschreibung
The requested action was not taken because the server has insufficient system storage. The server cannot accept more mail until storage is freed.
Wann Sie es sehen
When the mail server's disk is full or the recipient's mailbox has exceeded its storage quota. The server cannot store additional messages.
Wie man es behebt
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.
Wesentliche Unterschiede
221 is a 2xx Positive Completion response, while 452 is a 4xx Transient Negative response.
SMTP 221: The server is closing the transmission channel. This is the normal response to the QUIT command, indicating a graceful end to the SMTP 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 221 when after sending the QUIT command at the end of a mail session. The server acknowledges the disconnect and the TCP connection will be closed.
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.
Wann welchen verwenden
For 221 (Closing Connection): No fix needed — this is the expected response when ending an SMTP session. If you see this unexpectedly, the server may be shutting down or timing out idle connections. 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.