> My point is to understand why Postfix (on MX backup) store email > into mailbox and does not queue them.
On the backup MX: DO NOT list the domain in mydestination, virtual_alias_domains, or mailbox_domains parameters. These list domains for local delivery. DO list the domain in relay_domains DO NOT list the valid recipients in virtual_mailbox_maps, or virtual_alias_maps. These list local recipients. DO list valid recipients in relay_recipient_maps http://www.postfix.org/ADDRESS_CLASS_README.html On the other hand, most folks these days think a backup MX is more trouble than it's worth due to the way they are abused by spammers. -- Noel Jones
