Set up a Zimbra account on Outlook for Android app

Source:
https://support.microsoft.com/en-gb/office/set-up-email-in-the-outlook-for-android-app-886db551-8dfa-4fd5-b835-f8e532091872#tab=bkmk_manual

In Outlook for Android, go to Settings Settings > Add Account > Add Email Account.

Enter email address. Tap Continue.

Tap Setup account manually if available, and then on the email provider page choose Exchange and toggle Advanced Settings on.

Enter your server setting details, if available and then tap the checkmark icon.

Server settings:

• Server host name: if you have an @his.com or @hers.com address : use "mail.his.com"
  or if you have your own domain like "domain.ext" use the format: "domain-ext.his.com"

Incoming Server Settings

• Domain\Username: Enter your full email address, such as yourname@yourdomain.com.

*Password: Use the password that you use to access your email.

• Server: IMAP: if you have an @his.com or @hers.com address : use "mail.his.com"
  or if you have your own domain like "domain.ext" use the format: "domain-ext.his.com"

• Port: Use 993.

• Security type: Select SSL/TLS or make sure the Use secure connection (SSL) checkbox is checked, then tap Next.

Outgoing SMTP Server Settings

• SMTP Server: if you have an @his.com or @hers.com address : use "mail.his.com"
  or if you have your own domain like "domain.ext" use the format: "domain-ext.his.com"

• Security Type: Choose SSL/TLS.

• Port Number: Enter 465. Tap Next. If you are unable to use port 465, try port 587.

You may be prompted to enter your email account password again or agree to/activate any necessary permissions.