Thank you for the clarification Matus. I appreciate it! On Wed, Apr 1, 2020 at 5:31 AM Matus UHLAR - fantomas <uh...@fantomas.sk> wrote:
> On 31.03.20 16:59, Linda Pagillo wrote: > >Guys, I have another question. This is in reference to the response that > >Bob Proulx gave me. He said that, " One critical item is that the > >relay_recipient_maps must be kept in sync across all of the systems". Why > >is this critical? > > It's partly described at > http://www.postfix.org/postconf.5.html#relay_recipient_maps > > many spammers try to use backup MX servers to deliver spam. > > If your backup MX accepts spam that your primary MX would rejects because > of > non-existent user, your backup MX would need to send back bounce, which > whould make it spam source, and it could appear on blacklists. > > Dropping such mail is not a good thing, since that mail could get "lost" > where sender believe mail was accepted (by backup MX), while recipient > would > not see it (because it was refused by primary MX). > > Thus, knowing users is crucial to have. > > I persinally believe that if you really need backup MX, you should do at > least some kind of recipient verification. > > -- > Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ > Warning: I wish NOT to receive e-mail advertising to this address. > Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. > Windows 2000: 640 MB ought to be enough for anybody >
