A server response code is included in the log entry for each message.
| Code | Description | Type |
|---|---|---|
| 1 | No error; success. | Plex |
| 0 | No Errors,Sucess | SMTP Server |
| 211 | System status message. | SMTP server |
| 214 | Help message formatted for human reader follows. | SMTP server |
| 220 | SMTP service ready. | SMTP server |
| 221 | The connection to the server has closed. | SMTP server |
| 250 | The mail server has successfully delivered the message. | SMTP server |
| 251 | Recipient is not local to the server, but the server will accept and forward the message. | SMTP server |
| 252 | Recipient can't be verified, but the server will accept the message and attempt delivery. | SMTP server |
| 354 | The server is ready to accept the message after you have given it "From" and "To" information. | SMTP server |
| 421 | The service is not available. | SMTP server |
| 450 | Requested command failed because the recipient's mailbox is unavailable. | SMTP server |
| 451 | The command was aborted due to a server error. | SMTP server |
| 452 | The command was aborted because the server has insufficient system storage. | SMTP server |
| 500 | The server did not recognize the command due to a syntax error. | SMTP server |
| 501 | A syntax error was found in the command arguments. | SMTP server |
| 502 | The command issued by the email server is valid but not activated on this server. | SMTP server |
| 503 | The server encountered a bad command or sequence of commands. | SMTP server |
| 504 | The command and parameter issued by the email server are both valid, but the parameter is not implemented or an additional parameter is missing. | SMTP server |
| 550 | The user does not have permission to send. | SMTP server |
| 551 | Recipient is not local to the server. Server responds with a forwarding address that should be tried. | SMTP server |
| 552 | The action was aborted because storage allocation was exceeded. | SMTP server |
| 553 | A domain is not specified in the email addresses of any of the recipients. | SMTP server |
| 554 | The transaction failed without a clear reason; unexpected error. | SMTP server |
| 9009 | Failed to log into the specified SMTP server. | Plex |
| 9010 | The server did not recognize the command due to a syntax error. | Plex |
| 9998 | The server did not recognize the command due to a syntax error. | Plex |
| 9999 | The server did not recognize the command due to a syntax error. | Plex |