Multitasking is a farce. When working on a text document, I lose my train of thought with each Pavlovian bell ringing in new messages. Who could it be? Is it something good? Of course I switch to Outlook to find out. I don't just waste time time, I lose my train of thought and progress.
For the simplest solution, I could just close Outlook. But I don't want to deal with opening and closing that application regularly, so I could just turn off all sound. But those desktop alert notices still pop up and pose a distraction, and I might need audio in other programs. Here's how to turn off Outlook's email alerts for new messages. Plus, you can set up custom rules to generate alerts only when important people send messages. Switch to Outlook when you finish other work. Single-tasking is the future.
Choose Tools, Options, and click E-mail Options. Click Advanced E-Mail Options. Uncheck the box to play a sound when a new item arrives, change the mouse cursor, show an icon in the notification area, and display a Desktop Alert. Outlook should now be disturbance-free, letting you focus on other tasks.
If needed, override these settings to enable alerts from a specific person; maybe you're expecting messages from an on-deadline client. Simple mail rules can generate these sounds and even restore the often-intrusive Desktop Alerts. Choose Tools, Rules and Alerts, click New Rule, and pick one of the Stay Up to Date options. Create this rule just like any other, adding one or more contacts and picking a specific alert sound.