Auto-complete is a feature of the MUA (Mail User Agent) that your users may be using. You didn't specify.
Originally Posted by yonatan
I'm primarily using SeaMonkey, others are using Outlook. If and when I get time to figure out how to get Seamonkey hooked into the Zimbra LDAP, it auto-completes as you type.
Outlook requires a CTRL K after typing a portion of the address.
Ben Franklin quote:
"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."