Sending email with using “from” header

Question

I sent email with header "from" as: my_friend_email@example.com and when I received it, mail from his address was there. Example how headers looks like:

$headers .= 'From: MyFriendsEmail<my_friend_email@example.com>' . "\r\n";

Questions: Can he see I have sent email from his address? Is it legal?

I have tried to check maybe it's sent from my ftp but it's not :P

Answer 1

不可以，除非收件人与他联系，否则他不能（因为它不在他的邮件帐户中）。