Response codes for SMTP

As i mentioned in my last post SMTP commands are answered with numeric responses. Here I have included some common SMTP server response codes and what they mean. If at any stage in an SMTP transaction there is an error, it will have a unique code assigned to it so the user can hopefully determine why it has happened. However the response codes are not always errors, SMTP will also output a success code.

The first digit of the response denotes whether it is good, incomplete or simply bad.
2 = success - 4 = temporary failure 5 = permanent failure

•  
  • 211 - System status or system help reply
  • 214 - Help message
  • 220 - The SMTP service is ready
  • 221 - SMTP is closing the transmision channel
  • 250 - The command has been completed
  • 354 - OK to transmit message
  • 450 - Command can not be completed because mailbox is busy.
  • 451 - Command has been aborted because of an error
  • 452 - Command has been aborted because the receiving server is out of disk space
  • 500 - Syntax Error
  • 550 - Mailbox is not available or doesnt exist
  • 552 - Command was aborted because the recipient exceeded their storage quota
  • 554 - The transaction has failed.
  • 556 - Transaction failed due to bad weather! (only joking)