Annette Iafrate, an executive with Constant Contact, gives the following smart and sensible tips for improving e-mail marketing results:

1. Use your own permission-based list.

2. When people sign up, let them know what kind of e-mails they will receive from you and when they will get them.

3. Keep your list up-to-date by removing inactive subscribers or sending them a one-time e-mail asking them to confirm their interest.

4. Determine the optimal frequency by asking yourself how frequently your customers think about or use your product.

5. Keep your content fresh, useful, and relevant.

Source: Target Marketing magazine