King Cao:
> I see your point. But current MX support will also cause this
> problem. For example, if we configure the transport: "example.com
> smtp: mx.example.com:25" which is supported by all Postfix version.
> smtp daemon(smtp/smtp_connect.c) will query all MX records of
> "mx.example.com" and try these mx records one by one according to
> preference.
That is how SMTP is defined in the Internet mail standard.
Postfix is optimized for the common scenario.
> My suggestion is that can we put such MX records into transport
> directly to avoid DNS querying?
There is no need to optimize Postfix for uncommon use cases. Spammers
can use separate transports each with their own source IP address,
fallback relay settings, and so on.
Wietse
