There are certain service providers that generate temporary email addresses for a short period of time, like a few hours to a few days. Such addresses are known as "Disposable Email Addresses". Generally, disposable emails are created to receive initial account activation or confirmation emails for sites like discussion forums, e-shopping etc. and dispose off automatically after a given time period. Sending emails to such addresses increases the bounce rate so it is not advisable to send emails to "Disposable Email Addresses".