If you are unable to modify your outgoing mail settings in Outlook for Mac as described here (i.e. Exchange users), you can still set up tracking in Outlook for Mac using SMTP Relay by creating a second account with alternative POP credentials. Note that this method will set up a second account for sending (and tracking) only -- the inbox will be empty and can be used to track and send outgoing mail.
Setup is as simple as modifying your outgoing mail settings. To start, you will need a Bananatag account, which is available for free at Bananatag.com.
Once you've created have your account, log in to Bananatag and select Account and then Settings from the left hand menu, then click SMTP Relay on the main window:
Note: If you do not have Send Direct set up, you will be prompted to enable it before continuing.
Under the SMTP Relay settings, enter your desired password and select Save New Password.
You'll receive a confirmation (as above) with the correct SMTP settings for your account.
SMTP server: smtp.bananatag.com
Open your Outlook for Mac Mail Settings by clicking Outlook > Preferences > Accounts, select the + icon on the lower left, and add a new Other Email account.
Enter your details after unchecking Configure automatically, and set up a POP server. Set the Incoming server to firstname.lastname@example.org. Set your Outgoing server with the information provided in your Bananatag account in Step 1, and click Add Account.
You can give this account a Description so it's clear later on when you're sending your emails that this account is set up with tracking. Once you've done this, click on More Options:
Note: In this step, you can also use the Advanced button to access settings for how frequently this account will fetch mail, and disable the checkbox to check for messages every two minutes.
In this window, select User Name and Password Authentication, and enter your username, and the password you selected in Step 1. Then click OK and close the preferences window.
Your Outlook for Mac is now set up with Bananatag, and your emails sent from this account will be automatically tracked. You will receive an email notification when your emails are opened, as well as notifications when any links in your emails are clicked.
You can send yourself a test email, and your compose window should now have an option to switch the from address to enable/disable tracking.
Note that you may see a Send/Receive error as this alternative account is unable to receive mail, only track and send it.
For users on a free plan, your first 5 emails sent from your tracking profile each day will be tracked. If you require more daily tags, you can upgrade your Bananatag plan.