----- Original Message ----- > From: "Reindl Harald" <h.rei...@thelounge.net> > To: postfix-users@postfix.org > Sent: Saturday, 11 June, 2011 6:23:59 PM > Subject: Re: unverified_recipient_tempfail_action = permit > > > > Am 11.06.2011 16:55, schrieb Wiebe Cazemier: > > That's not what I meant. I meant that 99% of the time, the primary > > server > > will be up and recipient address verification will work to reject > > (spam) > > messages to unknown users. Those two scenario's you mentioned are > > when > > the primary is down or otherwise deferring. And those cases happen > > 1% of > > the time (figure meant to be illustrative). > > so you do not need any backup-MX because if your primary > is not available the edferring happens on the sender > > this is teh way smtp works
Default defer time for most SMTP servers is only 3 to 5 days, that is not long enough for me. > > > So if you would accept mail when the primary is down, you may very > > briefly > > create backscatter, but it allows you to operate a backup MX server > > without > > syncing recipient maps, or have any other knowledge about it > > nut the backup-mx is really useless if it depends on the primary one > for > proper working and in the reality a backup-mx is useless, really I kind of disagree. It doesn't rely on the primary for proper functioning, it just makes use of knowledge of the primary when it can. > > only if you have some database-driven configuration with a > replications > salve on the backup-mx it makes any sense because your configuration > is independent, if you are using a spam-filtering appliance as > example > the backup-mx is the dead of your spam-filtering and if you are using > greylsiting the backup-mx is also the dead of well working service > becasue if the primary mx ansers with "temporary problem" the sending > server will try your backup-mx and if both of them doing greylist > you are playing something like ping-pong with the senders without > any sync between the servers > >
