Autocomplete is a new feature of Outlook introduced in Outlook XP. It
is enabled by default, but you may have disabled it somehow.
Here is the description of the Autocomplete feature and how to
AutoComplete Addressing: As an e-mail address, e-mail alias, or as an
entered name, Outlook offers to complete the address, alias, or names,
based on addresses, aliases, or names that e-mail messages that you
have previously sent to. This is enabled by default, and you can
disable it by clicking Options on the Tools menu, clicking E-mail
Options on the Preferences tab, and then clicking Advanced E-mail
There are two different types of autocomplete. One is to have it
complete the name based on emails you have sent before (see above
description) and the other is to complete the name based on names
found in your address book. There are two separate options under
"Advanced Email Options" for turning these on. Check "Automatic Name
Checking" to have it resolve names from your address book and check
"Suggest Names While Completing To, CC, and BCC Fields" to have it
resolve names from previously sent messages. When using the name
checking autocomplete, you have to press [TAB] after typing part of
the name and it will take a few seconds before it resolves the name
and replaces it with a match from your address book. The other type
will actually make suggestions as you type.
If you've checked both of these options and it's still not working,
you may have a problem with your installation. Please read the Technet
articles listed below for a couple of common problems that lead to
this function not working and how to correct them.
I hope this helps to answer your question regarding the autocomplete
function of Outlook XP. Please don't hesitate to "ask for
clarification" if I can be of further assistance on this question.
Autocomplete May Not Function After Upgrading Outlook 2000...
Pressing TAB Does Not Produce Acceptance of Autocomplete...
Autocomplete Does Not Include All Email Addresses...
Outlook Slow to Resolve Name When Cache is Full
Microsoft Technet: Outlook Autocomplete