XF 1.2 Mass Email Not Working

[JoshSmith100]

Ive been trying to send a mass email but its not working. It says this in the server error log

Error Info Zend_Mail_Protocol_Exception: Incorrect authentication data - library/Zend/Mail/Protocol/Abstract.php:431
Generated By: JoshSmith, Yesterday at 10:58 PM

I thought it was a host problem but they claim that a experienced Xenforo developer can help out. So guys, how can I fix this error?

 

[Jeremy]

Your SMTP credentials are incorrect.

 

[JoshSmith100]

What does that mean? I have no idea what SMTP is. How can I find these credentials?

 

[whynot]

Hopefully you have a control panel to your hosting account.
You should be able to find how to use SMTP . (Incoming, outgoing)

 

[Jeremy]

You will want to edit your email options; you most likely are using SMTP to send emails. The username and password are wrong.