I have experience self hosting for incoming mails; outgoing mails are sent via mailchimp. We have had this setup for several years. It is not difficult to setu

I have experience self hosting for incoming mails; outgoing mails are sent via mailchimp. We have had this setup for several years. It is not difficult to setup, emails are delivered reliably, and email delivery cost is negligible. Some of our users use Outlook / Thunderbird / Apple Mail as a client, some use GMail as a client (check external mail / send as user) and some use Rainloop which I set up on the mail server.