When your most important contacts use outlook, it does not matter what you do. Sending and receiving email when almost nobody else is sending and receiving is only small help.
Some problems are not solved by individual choice. If 30-40% of your important contacts use service that is down, your ability to work goes down dramatically.
I have currently important 3 daily contacts down they use MS services extensively contacted and said they can't do much of anything because their work process and the process of their contacts is down.
Enough of my contacts use Gmail. But both of these have more uptime than my self-hosted email.
If the person I'm contacting is using Outlook then I assume it's going to be unreliable anyway.
Personal email is almost exclusively for OTP, reminders/invoice.