Hello,

can courieresmtpd validate existence of mail addresses in the domains that are not local (listed in hosteddomains/locals)?

We want to split SMTP servers from MX servers, and I'm curious if it wouldn't result to accepting recipients that don't exist and are reject by "550 user <...> unknown" messages.

We may distribute users' lists onto the SMTP servers of course, but we'd like to keep delivery on the MX servers.

Another question is - can courieresmtpd validate existence of addresses provided in mail from: in the same way as it validated rcpt to: ? E.g. if rcpt to:<nosu...@example.com> is rejected with 550, mail from:<nosu...@example.com> could be rejected with the same error.

Of course this can be only applicable to locally known domains.

And btw: can courier reject non-existing domains in rcpt to: even for users with relaying privileges? mail from:<> nonexisting domains is rejected (if BOFHCHECKDNS is 1). However rcpt to: is not validated the same way, so it's quite often that users send mail to nonexisting domains.

... we are using a bit old courier, so it's possible that this is already implemented. However I haven't seen any mention of these...