Suppose that I send an E-mail to someone.
Is it possible to fake mail server address - for example, while I used my own local mail server, I send it as if it was sent from Microsoft mail server. (I know that I can fake my mail address - I am asking if it is possible to feign mail server.)
Yes. If you write a program that connects to an SMTP server, you can usually just set To and From variables to anything you want and the server will try to send the email.
Phishing attacks are usually done this way to get you to click on a link to a fake website impersonating a bank, eBay, etc. Email clients like Gmail try to determine the validity of the email (probably by IP/domain of known hosts) and can mark the email as spam.
A way to catch something like this is to look at the entire email header. Something coming from Microsoft.com should pass through servers in Redmond, or at least in Washington state as a first hop. If you discover that the first hop is a server in Russia or China, you've found someone phishing.
