PHP SMTP for mailgun on Linux Hosting not working

I'm on basic linux cpanel hosting with GoDaddy. I've signed up with mailgun to allow me to send out registration emails from my website. I've built and tested my website on my local server with mailgun's smtp details and it works perfectly.

 

However, when I upload my code to godaddy and test the email send, it doesn't send or error. I've checked mailgun's logs and there isn't even a request to send, so it's not on the mailgun side.

 

I read somewhere that I have to use port 25, so I tried that and it still isn't working on go daddy (but works on my local development environment).

 

Is PHP SMTP disabled for basic linux hosting or something? I've already confirmed that all mailgun details are correct and my domain is correctly setup.

 

Thanks for any help!