Greg Owen <[EMAIL PROTECTED]> wrote:
> When will qmail decide to back off the primary MX and try to use
>lower priority MX hosts?
When it decides that the primary is permanently down.
> In particular, if the primary MX allows a connection and immediately
>drops it, will qmail ever decide to try the next MX?
No.
> But it seems that qmail isn't backing off, probably because it gets
>a connect rather than getting a refusal.
Correct.
> Should qmail be backing off? Is accepting+dropping connections
>documentably wrong, that I should complain to them about it? What's the
>deal?
RFC 974 is unclear on this. It says:
If the list of MX RRs is not empty, the mailer should try to deliver
the message to the MXs in order (lowest preference value tried
first). The mailer is required to attempt delivery to the lowest
valued MX. Implementors are encouraged to write mailers so that they
try the MXs in order until one of the MXs accepts the message, or all
the MXs have been tried. A somewhat less demanding system, in which
a fixed number of MXs is tried, is also reasonable.
It doesn't say mailers MUST try alternative MX's, but it does
encourage trying others when one fails to accept a message.
See also:
http://www.ietf.org/rfc/rfc0974.txt
-Dave
