SMTP
and Mail server error codes
Short description of SMTP/ESMTP error codes and
error messages
How often do you get "FATAL ERROR: Could
not send your message. Error #550" when sending email?
What does "Error #550" mean? Ordinary users may only understand what
their e-mail was not sent. Why and what to do?
You need to know the structure of thes error codes. A mail server will reply to every request
a client (such as your email program, like Outlook Express, Eudora, Atomic Mail
Sender) makes with a return code. This code consists of three numbers. First
digit tells whether the server accepted the command and if it could handle it.
There are five possible values:
1.
Mail server has accepted
the command, but does not yet take any action. A confirmation message is
required.
2.
Mail server has
completed the task successfully without errors.
3.
Mail server has
understood the request, but requires further information to complete it.
4.
Mail server has
encountered a temporary failure. If the command is repeated without any change,
it might be completed. Try again, it may help!
5.
Mail server has
encountered a fatal error. Your request can't be processed.
Second digit tells more. There are six possible
values:
1.
Syntax error
2.
Information reply (for
example to HELP request)
3.
This digit refers to the
status of connection
4.
non-used
5.
non-used
6.
This digit refers to the
status of the mail server
The third digit tells more then second again. It shows more graduations of the
mail transferring status. Combination of these three digits gives us detailed
list of ESMTP server response codes, as layed down in
RFC 821 and later extensions.
Error code |
SMTP/ESMTP error message description |
211 |
System status, or system help reply |
214 |
Help message |
220 |
Service ready |
221 |
Service closing transmission channel |
250 |
Requested mail action okay, completed |
251 |
User not local; will forward to |
354 |
Start mail input; end with . |
421 |
Service not available, closing transmission channel |
450 |
Requested mail action not taken: mailbox unavailable |
451 |
Requested action aborted: local error in processing |
452 |
Requested action not taken: insufficient system storage |
500 |
Syntax error, command unrecognized |
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 |
551 |
User not local; please try |
552 |
Requested mail action aborted: exceeded storage allocation |
553 |
Requested action not taken: mailbox name not allowed |
554 |
Transaction failed |