| 2xx/3xx class - Success They
are SMTP protocols successfull answers
 
4xx class - Temporary Errors
| 200 | 200 Non standard
success response Non
standard success response
 |  
| 211 | 211 System status,
or system help reply System
status, or system help reply
 |  
| 214 | 214 Help message Help
message
 |  
| 220 | 220 
Service ready Service ready
 |  
| 221 | 221 
Service closing transmission channel Service closing transmission channel
 |  
| 250 | 250 Requested mail
action taken and completed Your
ISP mail server have successfully executes a command and the DNS is
reporting a positive delivery.
 |  
| 251 | 251 User not
local: will forward to Your
message to a specified
email address is not local to the mail server, but it will accept and
forward the message to a different recipient email address.
 |  
| 252 | 252 Recipient
cannot be verified Recipient
cannot be verified but mail server accepts the message and attempts
delivery
 |  
| 354 | 354 Start mail
input and end with . Indicates
mail server is ready
to accept the message or instruct your mail client to send the message
body after the mail server have received the message headers.
 |  Those
codes are temporary error message. They are used to tell client sender
that
an error occured but he can try to solve it but trying again, so in
most cases, clients that
receive such codes will keep the mail in their queue and will try again
later.
 
 
5xx class - Permanent Errors
| 421 | 421 
Service not available, closing transmission channel This
may be a reply to any command if the service knows it must shut down.
 |  
| 450 | 450 Requested mail
action not taken: mailbox busy or access denied Your
ISP mail server indicates
that an email address does not exist or the mailbox is busy. It could
be the network connection went down while sending, or it could also
happen if the remote mail server does not want to accept mail from you
for some reason i.e. (IP address, From address, Recipient, etc.)
 |  
| 451 | 451 Requested mail
action aborted: error in processing Your
ISP mail server indicates
that the mailing has been interrupted, usually due to overloading from
too many messages or transient failure is one in which the message sent
is valid, but some temporary event prevents the successful sending of
the message. Sending in the future may be successful.
 |  
| 452 | 452 Requested mail
action not taken: insufficient system storage Your
ISP mail server indicates, probable overloading from too many messages
and sending in the future may be successful.
 |  
| 453 | 453 Too many
messages Some
mail servers have the
option to reduce the number of concurrent connection and also the
number of messages sent per connection. If you have a lot of messages
queued up it could go over the max number of messages per connection.
To see if this is the case you can try submitting only a few messages
to that domain at a time and then keep increasing the number until you
find the maximum number accepted by the server.
 |  This
are permanent error codes. Mail transfer is definitly a failure. No
other try will be done.
 
| 500 | 500 Syntax error,
command unrecognized or command line too long |  
| 501 | 501 Syntax error
in parameters or arguments |  
| 502 | 502 Command not
implemented |  
| 503 | 503 Server
encountered bad sequence of commands |  
| 504 | 504 Command
parameter not implemented |  
| 521 | 521 
does not accept mail or closing transmission channel You
must be pop-authenticated before you can use this SMTP server and you
must use your mail address for the Sender/From field.
 |  
| 530 | 530 Access denied A
sendmailism ?
 |  
| 550 | 550 Requested mail
action not taken (Relaying not allowed, Unknown recipient user, ...) Sending
an email to recipients
outside of your domain are not allowed or your mail server does not
know that you have access to use it for relaying messages and
authentication is required. Or to prevent the sending of SPAM some mail
servers will not allow (relay) send mail to any e-mail using another
company’s network and computer resources.
 |  
| 551 | 551 User not
local: please try  or Invalid Address: Relay
request denied |  
| 552 | 552 Requested mail
action aborted: exceeded storage allocation ISP
mail server indicates, probable overloading from too many messages.
 |  
| 553 | 553 Requested mail
action not taken: mailbox name not allowed Some
mail servers have the
option to reduce the number of concurrent connection and also the
number of messages sent per connection. If you have a lot of messages
queued up (being sent) for a domain, it could go over the maximum
number of messages per connection and/or some change to the message
and/or destination must be made for successful delivery.
 |  
| 554 | 554 Requested mail
action rejected: access denied |  
| 557 | 557 Too many
duplicate messages Resource
temporarily unavailable Indicates (probable) that there is some kind of
anti-spam system on the mail server.
 |  |  |