Jerry:
> On Mon, 4 Jul 2011 04:48:44 -0700 (PDT)
> Charlie Orford articulated:
>
> > unverified_recipient_tempfail_action = permit? would have solved this
> > problem with the small penalty of a brief period of potential
> > backscatter.
>
> The "potential backscatter" is enough to turn me off on the proposal.
> Now, if you could develop something that did not involve that problem
> then I think it might be given a warmer welcome by the community. Then
> again, that is my own 2? on the matter.
My previous reply suffered from damage while editing. This is an
attempt to fix it.
The problem with recipients not in the verify cache is easily
addressed with existing Postfix features.
With unverified_recipient_tempfail_action=defer_if_permit or defer,
Postfix will pass mail for recipients that were added to the verify
cache up to 31 days ago. In addition, Postfix attempts to refresh
information after 7 days so that active recipients don't expire.
These are the default settings, which you can change.
To avoid the expiration of known recipients after 31 days, you can
increase the address_verify_positive_expire_time setting to a larger
value. If you set the expiration time too long, there will be
backscatter after a recipient's account is terminated. Don't set
it to years.
That leaves the rare case of a recipient who almost never receives
email. I think it would not be a problem if such email is delayed
by a few hours when the primaty MX host is down.
Wietse
