All email scripts on remote server not sending emails

Something is effecting all send mail scripts across our website. We recently had our hosting providers run a test with a php.info file. I believe since the tests were performed something has effected the site and the email scripts are not sending the emails. everything is working fine on my local testing server. we have numerous send email scripts that are triggered by actions across our website, admin, and customer account pages.

I have the support team from Fasthosts ( our hosting provider ) currently running tests bit I just wanted to reach out to see if anyone can help with this or have any advice to what might cause this.

Thanks in advance!

Check your server IP or domain hasn't been blacklisted - we recently had an issue with Spamhaus listing our new server IP address and it immediately stopped all emails from sending via the webforms. Turned out there was no reverse IP (PTR record) set up for the server but now that's been done we've had no further issues. You can check blacklisting here: https://mxtoolbox.com/blacklists.aspx

Also, are the emails sending from an email address using the same domain as the website the form is on? For example, if it's a contact form do you have it set to come from e.g. "noreply@yourwebsite.com" or does it come from "sender.name@theirdomain.com"? If the latter, this isn't allowed by most ISPs now because of spoofing issues. If your webform is on www.mydomain.com/contact.php then you must set the email script to send from anyaddress@mydomain.com.

Thanks Mags.. It was indeed Spamhaus that had blacklisted our IP address. I discovered it when I ran a send mail script in debug mode and the log results gave us the problem. I will look to set up a PTR record as you mentioned.