A division of my institution has changed its email addresses to a simpler format (it's about time!). I use the Mac Mail program that automatically pops up possible names/email addresses when I type in a name (or part thereof).

Although they have been deleted from the institutional system, the old email addresses still show up on my work computer. They are not in my address book. Any suggestions as to where they are hiding?

This is a real nuisance. Although I try to be sure to select the new address, occasionally I get the old one and find out only a day or two later that the email did not go through.