The problem you are having is due to Port 25 blocking. This blocks any 3rd party outgoing mail servers from being accessed while connected to your ISP network via Dialup, DSL or Cable. Many ISP's (Internet Service Providers) are blocking what is called "Port 25" which is the port used to send e-mail. They have chosen to do this to cut down on the amount of "SPAM" mail that is sent. All e-mail sent via the Internet is routed through the port 25, the channel used for communication between a mail client and a mail server. Therefore, if your ISP is blocking the port, eMail Verifier will be unable to fully test e-mail addresses, eMail Verifier can check the syntax of the e-mail addresses and whether the domain they belong to exists but the last step, connecting to the address MX Exchanger, can't be performed.
Unfortunately, there is nothing we can do to change this. The port 25 is the standard for sending messages and the one eMail Verifier uses. The only solutions are either to contact your ISP and see if they can remove that block or switch to another ISP. Smaller local ISP's usually do not block Port 25. Here are some web sites that can help you find thousands of ISPs:
You can check with your dial-up provider to see if they are doing this. Here are a few of the major ISP's that block Port 25:
AT&T (can be unblocked at the request)
Comcast (Offer a Business Class account with full access to port 25
Verizon (can be unblocked at the request)
You can check whether you are affected by port blocking using Telnet.
Maintain clean mailing lists checking the validity of recipient's e-mails addresses. eMail Verifier can save time and money for businesses who send newsletters to their clients, nonprofit organizations who send bulletins to their members, or any person or business that needs to maintain a clean e-mail contact list.
eMail Verifier is your powerful solution for the standard "message delivery error." Email Verifier verifies every e-mail address from a given mailing list, allowing you to determine 80-90% of "dead" email addresses.
eMail Verifier works on the same algorithm as ISP mail systems do. Addresses for e-mail are extracted from a Domain Naming Server (DNS) and eMail Verifier tries to connect with SMTP-servers and simulates the sending of a message.
It does not send the message though - eMail Verifier disconnects as soon as the mail server informs the program whether the address exists or not. Email Verifier is a very effective piece of software that can verify over 10 e-mails per second .
It can verify single e-mails or huge lists. (eMail Verifier is multithreaded, providing high speed verifying).