A permission-based email is an e-mail sent to a person who has given the sender permission to send emails to their e-mail address. Often times people give permission by opting-in to receive emails by entering their contact information into the contact form on the sender's website. One example would be signing up for the bombbomb.com newsletter.
The term "double opt-in" means that the subscriber received a confirmation email when the contact form was filled out and that they confirmed their new subscription by clicking on a link. Failure to use permission-based contact lists or to keep clean contact lists (quickly removing invalid email addresses) may result in the sender being labeled as SPAM.
Permission-based email marketing is a best practice in the industry, delivering higher open, click-through, and conversion rates.
BombBomb.com provides a rich set of tools for building and maintaining permission-based lists including contact form creation, list management, list cleansing and subscriber management features.