[Dovecot] resilience suggestion

[Luca Corti]

On Fri, 2007-02-09 at 13:02 +0000, David Lee wrote:
> However, at many _other_ sites, the outlying email infrastructure may
> ensure that only email for existing users gets anywhere near the dovecot
> machine in the first place.  That is, by the time the email gets to
> "deliver", one is 99.99% certain that the user is a valid, existing one.
> (Furthermore, routine monitoring of the MTA queue can draw the sys.admin's
> attention to any email (should usually be close to zero at such sites)
> that has been sitting there for too long... a problem of some sort which
> requires attention anyway... and by my proposed "EX_TEMPFAIL" at least
> this possibly valid email has not been rejected.)

I think the short answer for this is that your MTA configuration is
broken, since it should accept mail only for existent users in the first
place. If this is an nscd bug it sholuld be fixed there, not by
introducing some hack into deliver.

> Meanwhile, for some sites, in some circumstances, "return EX_TEMPFAIL" may
> be more appropriate than a "5xx", to have available as an option.

I think it would be a nice addition to prevent misconfiguration or
temporary outages of other components (eg. database backends) to cause
legitimate mail loss while testing mail setups, but I don't think it
should be provided as a means to solve the problem describe.

ciao

Luca