ipn - fatal error emails

Recently we have started getting the following email from the cart:

Subject: IPN FATAL ERROR (1200682007_7HPP) #1

IPN FATAL ERROR::Could not establish fsockopen. Host Details =
ssl://www.paypal.com:443 (0)

Could somebody explain what causes this to generate this email. I'm trying to understand the process, So that I may explain it to the client better

It dark in here all alone :cry:

fsockopen is a PHP function used by Zen Cart to communicate back to the PayPal server to acknowledge an incoming IPN notification and to validate its authenticity.

The error you're getting says that communication was unsuccessful.

Some hosts block the PHP fopen Wrapper from being allowed to access external URLs. That setting would break your PayPal IPN functionality.

Ok. So if the problem is intermittent were would be the place to start when troubleshooting.

Your guess is as good as mine. What you're reporting is exposing a failure in communications. If that's intermittent, it suggests that it's something beyond the control of your Zen Cart software, and rather it's a server issue or a server-network issue, or an internet issue, or a PayPal issue.

I suppose you could turn on the Debug Log-To-File option in your PayPal module and inspect the logs when something unexpected happens. No guarantees that they'll help though ... all they can do is tell you that same issue... communication failed.