How to Verify Email Addresses When Your ISP Blocks the Port 25
It has become extremely rare for ISPs to leave the port 25 open for external connections. This makes it impossible for email verifier programs to check email addresses for validity using a direct Internet connection. We kept it in mind when developing the Advanced Email Verifier and implemented the alternate option for email verification in the program.
So, if your Internet service provider blocks the port 25, the Advanced Email Verifier has the ability to verify emails through the web script.
The web script is provided with the program. Using the script is possible if you have a web site where you can upload the script and if the script test confirms that the script is working [you can test the script directly from the Advanced Email Verifier]. If the test fails, it means that one or several functions on your site that are required for the work of the script are disabled. You can't use the script to verify email addresses unless you fix the errors.
If using the script is not possible for some reason [you don't have a website, you can't upload the script or the script does not work on your site], you can install the Advanced Email Verifier onto a Windows server with authentication records like FCrDNS records properly setup and enjoy the best performance of the program.
If you don't have enough knowledge to install and configure the Advanced Email Verifier on a Windows server, cosider using BPSocks email validation API key.