How do I disable AutoComplete in Microsoft Office Outlook 2007 and Outlook 2003?

Q: How do I disable AutoComplete in Microsoft Office Outlook 2007 and Outlook 2003?

A: I have a client who’s a partner in a law firm that runs Outlook 2003 and Exchange Server 2003. I showed him a recent article I thought he’d find interesting, “Lilly’s $1 Billion E-Mailstrom,” by Katherine Eban, on,, about an email problem experienced by another law firm. Someone in that firm wasn’t paying attention and sent a confidential email message to an unintended recipient with a name similar to the intended recipient’s. Instead of going to a lawyer named Bradford Berenson, the message went to Alex Berenson, a New York Times reporter. The confidential content ended up on the front page of the New York Times, in the story “Lilly Considers $1 Billion Fine to Settle Case,” on January 31, 2008.

My client wanted to know how he could avoid this type of situation. He said, “I’d love to know how to turn off the feature in Outlook that remembers addresses and names you've used before.” That feature is called AutoComplete (shown in Figure 1). It’s quite possible to make a mistake selecting a name from the cache or typing the letters of the name and selecting a similarly named, but unintended, recipient. You can disable AutoComplete easily from the GUI. In Outlook 2007 or 2003, select Tools, Options. In the Preferences tab, click E-mail Options, Advanced E-mail Options. Then clear the check box for Suggest names while completing To, Cc, and Bcc fields. (Figure 2 shows this check box still selected.) Click OK, and this change takes effect immediately; Outlook doesn’t require a restart.

Figure 2 also shows another productivity enhancement you might want to turn off—the Automatic name checking setting. This setting queries the Address Book and any contact folders specified as Address Books for names containing the letters entered in the recipient fields of a new message. If a unique match is found, Outlook completes the name of the intended recipient and underlines it. You can disable this setting by clearing the Automatic name checking check box. Once the check box has been cleared, Outlook won’t try to resolve text typed in the To, Cc, or Bcc fields with a contact from the Address Book. However, disabling this setting doesn’t prevent users from manually forcing the query by selecting the Check Names menu option. In Outlook 2007, Check Names is a ribbon button under the Message tab, while in Outlook 2003 it is both its own button as well as a menu option at Tools, Check names.

Following these simple steps might help my client’s law firm reduce the risk of inadvertently sending a message to the wrong recipient. And maybe the firm should make sure there aren’t any reporters in anyone’s Contacts folder.

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