For a better tracking of your communications with your contacts, My Book lets you know when an email has not been delivered (bounced).
Most of the time a bounce is caused by an issue with the receiving account, therefore you should find a different way than email to reach out to the recipients (ie phone call, text message) and let them know they are not receiving your emails.
Whenever you see the warning icon next to a contact's name, decide whether you want to reach out to the recipient to let him know or remove the contact record from your database.
Some of the reasons why an email can bounce are:
- the receiving mailbox is full
- the receiving server is temporarily unavailable
- the email has been blocked by the recipient (if they no longer want to hear from you)