On 30/03/12 22:56, Ron White wrote:
> Good afternoon,
>
> I have a bit of brain freeze I could use a jab in the right direction
> with.
>
> If Exim tries to deliver a message to a remote server and gets a 5xx
> code back, say 550 no such user, am I right in thinking the message
> should fail right away with an NDR, not remain on the queue being
> re-tried?
5xx means go away, do not retry.
> More sticky, if a remote server refuses connections from Exim - say it
> is firewalling off the connecting ip, should that fail at once or stay
> on the queue for x hours?
A firewalled off server is the same as a non-responsive server. Treated
as 4xx usually and normal retry rules apply.
> I'm sure in the first case it should fail at once, and in the second
> retry as the connection error could be transient, but I'd like to know
> for sure before I start troubleshooting.
rfc2821
quote
1yz Positive Preliminary reply
The command has been accepted, but the requested action is being
held in abeyance, pending confirmation of the information in this
reply. The SMTP client should send another command specifying
whether to continue or abort the action. Note: unextended SMTP
does not have any commands that allow this type of reply, and so
does not have continue or abort commands.
2yz Positive Completion reply
The requested action has been successfully completed. A new
request may be initiated.
3yz Positive Intermediate reply
The command has been accepted, but the requested action is being
held in abeyance, pending receipt of further information. The
SMTP client should send another command specifying this
information. This reply is used in command sequence groups (i.e.,
in DATA).
4yz Transient Negative Completion reply
The command was not accepted, and the requested action did not
occur. However, the error condition is temporary and the action
may be requested again. The sender should return to the beginning
of the command sequence (if any). It is difficult to assign a
meaning to "transient" when two different sites (receiver- and
sender-SMTP agents) must agree on the interpretation. Each reply
in this category might have a different time value, but the SMTP
client is encouraged to try again. A rule of thumb to determine
whether a reply fits into the 4yz or the 5yz category (see below)
is that replies are 4yz if they can be successful if repeated
without any change in command form or in properties of the sender
or receiver (that is, the command is repeated identically and the
receiver does not put up a new implementation.)
5yz Permanent Negative Completion reply
The command was not accepted and the requested action did not
occur. The SMTP client is discouraged from repeating the exact
request (in the same sequence). Even some "permanent" error
conditions can be corrected, so the human user may want to direct
the SMTP client to reinitiate the command sequence by direct
action at some point in the future (e.g., after the spelling has
been changed, or the user has altered the account status).
/quote
SMTP
http://www.ietf.org/rfc/rfc2821.txt (replaced by 5321)
http://www.ietf.org/rfc/rfc5321.txt
Extended error codes
http://www.ietf.org/rfc/rfc3463.txt
