> >> Received: from theguardian.com (regtreis.viverindia.com.br
> >> [31.172.134.4])
The remote SMTP client sent theguardian.com in the EHLO or HELO command.
31.172.134.4 is the client IP address. The Postfix SMTP server looks
up the domain name for that client IP address, regtreis.viverindia.com.br,
and uses that domain name only if it resolves to the remote client
IP address. Otherwise, the Postfix SMTP server will use "unknown" instead.
If you want to enforce that the HELO/EHLO matches the client domain
name, then Postfix does not do that.
Wietse
