A message that doesn’t get delivered promptly is said to have bounced. Emails can bounce for more than 30 reasons: the email address is incorrect or has been closed; the recipient’s mailbox is full, the mail server is down, or the system detects spam or offensive content. See hard bounce and soft bounce.

Building an Opt-In List, Building Relationships
If you aim for success, you must do everything within your means to achieve that. You just donít go on sitting there in your house complaining about not getting as much profit as you expect.