[Not Resolved] My forum won't send email to registering users

[Forces of Steel]

My users are having problems registering an account on my forum because none of them get an activation email in their inbox and I currently have the settings set to "Activation By Email". Can anyone tell me what could be the culprit and how I can fix that? Thanks.

[Adobe]

This user has been denied support.

What are you using for mail PHP or SMTP and go to ACP>Tools & Maintenance>System Mail Log>Post the errors here.

[Forces of Steel]

But there were no errors.

[Vernier]

Try the mail test: http://docs.mybb.com/Help-Mail.html

[Forces of Steel]

That script worked. So something has to be wrong with the board.

[Vernier]

Are you using PHP mail or SMTP mail?

Sometimes PHP mail may appear in the junk box. Try use SMTP mail if you can.

Admincp -> Configuration -> Settings -> Mail Settings -> Mail handler

[JordanMussi]

Get them to check their spam folders.

[Forces of Steel]

Ya I just tried configuring SMTP, but the SoB still isn't working. And no there is nothing wrong with the host's mail server. I tried sending mail using an email account with the host and that works.

And no spam mail or junk mail, either. The thing just is not working, simply put.

[Forces of Steel]

Bump.

[JordanMussi]

Reupload the following from a fresh mybb package:
./inc/class_mailhandler.php
./inc/mailhandlers/index.html
./inc/mailhandlers/php.php
./inc/mailhandlers/smtp.php