Question

I’m trying to email new registered users for email verification (PHP) but i don’t get it, why would an email be sent to SPAM, i already checked out similar questions and all answers are about Headers,

It seems a bit complicated for me to get known to those headers and how are they being verified,
By sender website ? lets say i sent as [e-mail] and the actual server domain is domain.com, how would it know? and is it one of the main reasons why it goes to spam ?
I am using VPS, does it has anything to do with it ?
I’m just trying to understand the clear/simple reasons of why would an email be checked as spam

and what if i sent from the server IP and not the domain itself

Answer 1

1) Check headers. You could use any email sending library such as PHPMailer (http://code.google.com/a/apache-extras.org/p/phpmailer/wiki/PHPMailer#Documentation_and_Resources)

2) Check hosting server. If your is using shared hosting then most probably it has been blacklisted by the email domain.