Background
I am working with email headers for spam detection.Each E-Mail header contains many "Received-from" fields,each "Received From" field added by an intermediate Smtp/Mail server in the path from Origin Of E-Mail to Destination of E-Mail.
Thoughts
I have read that Email delivery is done by Sender's Mail Server sending E-Mail directly to Receiptent's Domain Mail-Server(obtained IP address of receiptent Mail-Server through MX Query of Receiptent Domain)
Query
Can somebody explain,if the above method is right,then where does these Intermediate Mail-Servers come into picture and how does our E-Mail reaches to these intermediate Mail-Servers in the Internet.