I have an Exchange vm setup the last 3-4 years now. I use smtp2go for outgoing email. Works really well. I primarily use the system for alerts emails and mailing lists I use. If it breaks its an annoyance but nothing critical. I have a mail filter in front that all incoming mail goes through.
Put anything you don’t trust into their own VLAN. For me that includes the kids pc and iot devices. Give them only internet access with no access to other internal networks.