Zimbra Desktop 7.1.1 (build 10917) on Windows Vista Home Premium (64-bit) on Dell Studio Notebook computer. 4 GB RAM.
I have set up Yahoo! (works great), GMail (works great) and POP3 email accounts.
I click New icon and select New Message. In the FROM: section I select the POP3 account. The To:, CC: and Bcc:, if selected, are all greyed out. You can not select any of them. When you move the cursor over this area it becomes a circle with a slash through it. You can click in the address line of any of these and start to type and the address and get an error Autocomplete Failure! in the Title bar of the window.
I then selected the icon to compose in a separate window. Now I could get auto complete to respond and give me a list of names and addresses with the letters I had typed. The To:, CC; and Bcc: were still not available.
Now autocomplete works in the main Zimbra window with the POP3 account. I still can not access the Select Address dialog from the To: CC: and Bcc: buttons in either the main window, or when I compose in a new window.