emails not going out to all users

I have a few s开发者_开发百科cripts that send out emails to my users, and for some reason not all users are getting the email. The site is not live yet, so its no big deal yet but I dont understand why. I have set up a few fake accounts, one with my school email, one with hotmail and one with yahoo. When I sign up with my school email I recieve the welcome email, but I get nothing with the other email accounts. The same thing with my 'forgot password' email. Only my school email works, yahoo and hotmail arent working...

I'm running on a Linux server with Apache. Using PHP and the kohana framework 2.3.4

Thanks.

EDIT: I am displaying all errors, I dont have an error with the actually sending of the mail (I dont think) since I get it in my school inbox. Im running off a hostmonster server.

Also, the emails were being recieved at one point, but now they're not being recieved AT ALL from those inboxes

There's a lot of possibilities. If your php code isn't spitting out any php errors (make sure you have the following settings.

error_reporting=E_ALL
display_errors=on

If you're not getting any errors chances are the request is reaching your specified mail server (or sendmail). This means it's either a network based issue, or the receiving servers may be rejecting your email (spam detection?) Make sure you're sending out at least a basic from: header as well.

I don't know much about Kohana, but if it's not sending the emails like you wanted, you might want to take a look at PHPMailer.