SMTP / FTP / IMAP Codes
Searchable reference of SMTP, FTP and IMAP response codes.
| Protocol | Code | Meaning |
|---|---|---|
| SMTP | 211 |
System status / help |
| SMTP | 214 |
Help message |
| SMTP | 220 |
Service ready |
| SMTP | 221 |
Service closing transmission channel |
| SMTP | 235 |
Authentication succeeded |
| SMTP | 250 |
Requested mail action OK |
| SMTP | 251 |
User not local; will forward |
| SMTP | 354 |
Start mail input — end with <CRLF>.<CRLF> |
| SMTP | 421 |
Service not available, closing channel |
| SMTP | 450 |
Mailbox unavailable, try later |
| SMTP | 451 |
Requested action aborted: local error |
| SMTP | 452 |
Insufficient system storage |
| SMTP | 500 |
Syntax error, command unrecognized |
| SMTP | 501 |
Syntax error in parameters or arguments |
| SMTP | 502 |
Command not implemented |
| SMTP | 503 |
Bad sequence of commands |
| SMTP | 535 |
Authentication credentials invalid |
| SMTP | 550 |
Mailbox unavailable / permission denied |
| SMTP | 552 |
Message size exceeds storage allocation |
| SMTP | 554 |
Transaction failed |
| FTP | 110 |
Restart marker reply |
| FTP | 150 |
File status OK; about to open data connection |
| FTP | 200 |
Command OK |
| FTP | 211 |
System status / help |
| FTP | 215 |
NAME system type |
| FTP | 220 |
Service ready |
| FTP | 221 |
Closing control connection |
| FTP | 226 |
Closing data connection — file transfer successful |
| FTP | 227 |
Entering passive mode |
| FTP | 230 |
User logged in, proceed |
| FTP | 250 |
File action OK, completed |
| FTP | 331 |
Username OK, need password |
| FTP | 425 |
Can't open data connection |
| FTP | 426 |
Connection closed; transfer aborted |
| FTP | 450 |
Requested action not taken — file unavailable |
| FTP | 500 |
Syntax error, command unrecognized |
| FTP | 503 |
Bad sequence of commands |
| FTP | 530 |
Not logged in |
| FTP | 550 |
Requested action not taken — file unavailable / no permission |
| IMAP | OK |
Tagged success |
| IMAP | NO |
Tagged operational error |
| IMAP | BAD |
Tagged protocol error |
| IMAP | PREAUTH |
Server preauthenticated |
| IMAP | BYE |
Server is closing the connection |
| IMAP | + |
Continuation request |
About this tool
Reference table of every common SMTP, FTP and IMAP response — useful for decoding mail and file-transfer logs.