My ISP is blocking the port 25. I uploaded the script to my site and tested it. I get the result "Warning"? What does it mean? Can I still use the script to verify emails?
Yes, you can use the script if the test gives the "Warning" result. "Warning" means that the script is working but there is one or several issues with the functions necessary for the work of the script. The issue(s) is not critical and can be ignored. However, if you fix the issue(s), the script will work faster and the speed of email verification will increase.
Pay a special attntion to the Forward-confirmed reverse DNS (FCrDNS) verification. If the Forward-confirmed reverse DNS (FCrDNS) check fails, we do not recommend that you use the script to verify emails from such domains as @yahoo.co*, @live.com, @hotmail.com, and @aol.com because these ISP use FCrDNS lookup to authenticate the IP address the connection is coming from. If the FCrDNS lookup fails, the incoming IP address goes to a blacklist.
You cannot use the script if the test says "Failed". This means that one or several functions necessary for the work of the script are disabled. You can fix the issues, or upload the script to a different website.