At http://www.postfix.org/postconf.5.html :
---- smtpd_reject_unlisted_recipient (default: yes) Request that the Postfix SMTP server rejects mail for unknown recipient addresses, even when no explicit reject_unlisted_recipient access restriction is specified. This prevents the Postfix queue from filling up with undeliverable MAILER-DAEMON messages. An address is always considered "known" when it matches a virtual(5) alias or a canonical(5) mapping. *The recipient domain matches $mydestination, $inet_interfaces or $proxy_interfaces, but the recipient is not listed in $local_recipient_maps, and $local_recipient_maps is not null. *The recipient domain matches $virtual_alias_domains but the recipient is not listed in $virtual_alias_maps. *The recipient domain matches $virtual_mailbox_domains but the recipient is not listed in $virtual_mailbox_maps, and $virtual_mailbox_maps is not null. *The recipient domain matches $relay_domains but the recipient is not listed in $relay_recipient_maps, and $relay_recipient_maps is not null. This feature is available in Postfix 2.1 and later. ---- Where the sentence 'An address is always considered "known" when ...' precedes the list of circumstances, on first read, this seems to suggest - and allows the user to infer - that the following list is a list of circumstances under which 'An address is always considered "known"'. This is very confusing. Upon reflection, the opposite must be true, where this list of circumstances must be circumstances under which "An address is UNknown", where "the Postfix SMTP server rejects mail for unknown recipient addresses". I suggest an edit, to simply place the sentence 'An address is always considered "known" ...' *after* the list of circumstances.
