Follow these steps to set up Zimbra email in Outlook:
  1. To add an email address in Outlook 2013, first go to the File menu option near the upper left-hand corner within Outlook.

  2. With Info selected, click Add Account.

  3. Select Manual setup or additional server types and click Next.

  4. When asked "POP or IMAP," Select IMAP and click Next.

  5. For the incoming server, please use zimbra.proteonsoftware.org and port 993 with encryption SSL enabled.
    For the outgoing server, please use zimbra.proteonsoftware.org and port 465 with encryption SSL enabled.

  6. Fill out the information on this window. Your login is your email and email password. Security/Encryption is SSL.

  7. Go to the Outgoing Server tab and check the box that says My outgoing server (SMTP) requires authentication and ensure Use same settings as my incoming mail server is selected underneath that.

  8. Now, go to the Advanced tab and change the Outgoing server (SMTP) port to 465 and select SSL for the preferred type of encryption. Then, simply click OK.

  9. You will be returned to original “Account Settings” screen. From here, simply click Next.

  10. Outlook will now test your account settings. Once it has succeeded, simply click Close from the test window and then Finish to complete the process.