Postfix 2.8.4 imported into NetBSD-current

• Performance: a high load of DSN success notification requests could slow down the queue manager. Solution: make the trace client asynchronous, just like the bounce and defer clients.
• The local(8) delivery agent ignored table lookup errors in mailbox_command_maps, mailbox_transport_maps, fallback_transport_maps and (while bouncing mail to alias) alias owner lookup.
• Workaround: dbl.spamhaus.org rejects lookups with "No IP queries" even if the name has an alphanumerical prefix. We play safe, and skip both RHSBL and RHSWL queries for names ending in a numerical suffix.
• The "sendmail -t" command reported "protocol error" instead of "file too large", "no space left on device" etc.
• The Postfix Milter client reported a temporary error instead of "file too large" in three cases.