SMTP Status Codes and Error Messages from Error 502 to 503
SMTP status code – 502 – Command not implemented.
(also called SMTP Error 5.0.2)
SMTP Error 502 : The command or function issued by
your mail server is valid but has not been activated
(typically, it is not supported on this particular server).
SMTP status code – 503 – Bad sequence of commands. or This mail server requires authentication
(also called SMTP Error 5.0.3)
SMTP Error 503 : In the original standards SMTP Status
503 indicates that the commands have been sent in the
wrong order, for example your mail server has sent the
“Hello” command before sending the “Mail” command.
This can often be caused by a drop in network connection
just as your server was sending a command, resulting in
the ISP’s server not receiving it and consequently not
understanding the command that followed it.
Note : this error, particularly if repeated, can be indicative
of communications problems, such as a noisy line,
intermittent drops in network connections, intermittently
faulty router, etc… The typical pattern will be that you get
the error, then messages transmit without problems, then
you get error 503 again, etc…
SMTP Reply Code 503 is nowadays more often an
indicator that the SMTP server you are trying to use
requires authentication and you tried to send a message
without authentication (username + password). This
SMTP Error 503 is permanent in that the SMTP server will
not log any errors in its log and it will not retry – you will
have to resend the email using authentication. Example of
such an error : “SMTP Error (state 13): 503 This mail
server requires authentication when attempting to send to
a non-local e-mail address. Please check your mail client
settings or contact your administrator to verify that the
domain or address is defined for this server.”.
Above are list of SMTP Errors Codes and Status Codes along with Error and Warning messages from Error 502 to 503 received while performing certain operation against mail server applications or related products.
What are SMTP Error Messages?
Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (e-mail) transmission. SMTP protocol is used for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP.
In general, each SMTP error contains the following information:
• The SMTP Status Code or SMTP Error Codes or SMTP Reply Codes
• The message text. This text is usually returned with the Error code. Some messages employ word substitution, where the word substituted represents the system-replacement of a term more specific to the occurrence.
• An explanation of how the error may have occurred.
Hope this was helpful.
Information about SMTP Error Codes or Status Codes and Error Messages on Windows, Linux Operating Systems.