Confirmed permission in web marketing happens when someone implicitly or explicitly subscribes to your e-mail list, and you respond to the subscriber with an e-mail requiring the subscriber to confirm his interest by reading your intended usage and then clicking a confirmation link.
If the subscriber doesn’t confirm, his e-mail address isn’t added to your list, even if he explicitly filled out and submitted a form or physically signed your guest book.
Although confirmed permission is the most professional form of permission, it’s also the most difficult for subscribers to understand. Therefore, confirmed permission isn’t always suitable. Generally speaking, confirmed permission should be used when you want to be absolutely sure that your subscribers want your e-mail.
Confirmed permission is the appropriate level if
You send sensitive information.
Your subscribers tend to forget signing up.
You want to have a physical record of the subscriber’s authorization to send e-mail.
Confirmation e-mails generally have low response rates, so if you’re using explicit permission to build your list, you might lose subscribers who really want to be on the list but fail to read the confirmation e-mail and click the required link. The trade-off, however, is that your confirmed subscribers are more likely to receive and open your e-mails.