I haven't come across being able to get Outlook to remind you if it is not open. But if you start Outlook and minimize it to the taskbar any tasks, appointments that have a reminder set will be advised to you at the time you have specified.
OnePlus 5 review
Alice Saey's mesmerising animation for Dutch singer Mark Lotterman
iPad Pro 10.5in (2017) review
Comment booster votre iPhone ?