I'd like to suggest finding a way to allow users to choose their own default reply email address and/or email management program.
For instance, in my day-to-day work I have an email address relating to my employment in that role. I also happen to use Outlook when doing that job. For my own business I use a different application and I also have a completely different email addres, which relates to my business identity. I use my laptop most of the time for everything, whether doing my paid job or pursuing my own business.
Because MYOB uses Outlook by default, I have sometimes sent out invoices or statements to clients who are no doubt confused because my address seems unconnected to my business. Not to mention the fact that it's embarrassing and a bad look for me to record email traffic on my employer's email account, when it has nothing to do with it.
It's very inconvenient to have to change address details in Outlook every time I need to do accounts for my business. Surely it could be made much easier by allowing me to choose the program I want to use, with the email address I have for my business. How hard could that be? I can't be alone on this point.