Christmas spam from RESERVED IANA adressblock ?

If you want to file a spam complaint I suggest you do a whois for This is the external facing mail server that sent you the email. Most applications these days are built in layers so a web layer forwards the email to an email server, if the application is not designed to suppress the HELO from the web layer then you will see internal email routing information. As for the network side most networks filter out BOGONS so you would not get RFC1918 into your network.