Your inbox may be flooded with junk emails. Sometimes, though, you really need to know when a particular message will arrive in your Inbox. Fortunately, you can set / set some alerts in Microsoft Outlook to make sure you don't miss the most important messages.
To adjust the custom notifications, we will create one rule in Outlook in desktop. This method, unfortunately, will not work in the Outlook web app - if you use it, you just need to keep your inbox as clean as possible.
After you open Microsoft Outlook on your computer, click Home> Rules> Manage Rules & Alerts.
Click on "New Rule".
In the "Rules Wizard" window, select the "Apply Rule on Messages I Receive" check box, and then click "Next."
You can choose any terms you want. We will set up an email notification from a specific address. To do this, select the "From People or Public Group" check box, then click "People or Public Group" in the box below.
You can then select a contact from your address book or enter your email address, then click "OK".
Scroll through the options and select the "Display a Specific Message in the New Item Alert Window" check box. Then click on "A Specific Message" below frame.
Enter the message you want to display. You can use emoji if you want, so we've added two rotating lights emergency to be notified when a message is important. After entering your message, click "OK".
Click "Finish" in the "Rules Wizard".
By the window confirmation that appears, click "OK".
Click "OK" again to close the "Rules and Alerts" window and you are ready!
This rule will now apply whenever an email from address that you typed arrives in your inbox. A notification will appear, even if you have turned off desktop notifications.
Source of information: howtogeek.com