ISSUE:

You receive a kickback message that an email could not be delivered to multiple recipients.

The kickback email identifies the reason as, "Your email program is using outdated address information for the recipients.

CAUSE:

The email program's auto-complete contact list is created from the user's email history. It is not directly connected to the global contact list. Therefore, when the contact's information is changed, the auto-complete contact list becomes outdated.

SOLUTION:

Clear the auto-complete contact list.