On Wed, Apr 08, 2015 at 08:59:41AM +0200, Louis-David Mitterrand wrote:
> I manage a web site that sends price change alerts to subscribers using
> postfix with VERP to detect failed deliveries. When a bounce comes in it
> is fed to a perl script (through procmail) which increments the email's
> error count in the database until that count reaches 4 and the email is
> disabled.
>
> My problem is that sometimes delivery errors are transient (server
> change, etc.) but the error count is never reset on a successful
> delivery.
>
> What strategy could I use to detect a successful delivery in order to
> reset the error count?
A simple counter design is likely too naive. Instead track each
messages sent with a timestamp, and any bounces received. Drop
only users whose most recent non-bounced message *and* first bounce
after that are both sufficiently far in the past, and who since
then have accumulated enough bounces.
Apply a more stringent test for newly added users, dropping them
if the first ~2 mails bounce regardless of how much time has elapsed.
--
Viktor.
