| 100 |
Socket error. |
| 101 |
Socket timeout. |
| 102 |
Unable to resolve the SMTP server hostname. |
| 103 |
Unable to connect to the SMTP server. |
| 104 |
Server error; response not understood. For example, the message is poorly formatted, or the server is not SMTP. |
| 421 |
domain service not available, closing transmission channel.
|
| 450 |
Requested mail action not taken: mailbox unavailable. |
| 451 |
Requested action not taken: local error in processing. |
| 452 |
Requested action not taken: insufficient system storage. |
| 500 |
Syntax error, command unrecognized. (This may include errors such as a command that is too long). |
| 501 |
Syntax error in parameters or arguments. |
| 502 |
Command not implemented. |
| 503 |
Bad sequence of commands. |
| 504 |
Command parameter not implemented. |
| 550 |
Requested action not taken: mailbox unavailable. For example, the mailbox is not found, there is no access, or no relay is
allowed.
|
| 551 |
User not local; please try forward-path
|
| 552 |
Request mail action aborted: exceeded storage allocation. |
| 553 |
Requested action not taken: mailbox name not allowed. For example, the mailbox syntax is incorrect. |
| 554 |
Transaction failed. |