[Mesh] Email server setup- can anyone help?

I had thought that it might be more professional if we were able to email people from @peoplesopen.net addresses instead of just using our personal addresses. The current peoplesopen.net email setup is that there are forwarding rules (you can receive mail on a @peoplesopen.net address), but you can't send it. To be able to send emails, we need an email server. I've set up mailinabox on a ubuntu server, it's a pretty good combo of dovecot, a webmail interface, some spam stuff, and an admin panel with status checks. It will even automatically get letsencrypt certificates. However, setting up the DNS has proven to be very hard for me to get right. I've set up DNS for email and websites before, but never on such a complex setup with so many domains and things that need to keep working. I've tried a bunch of stuff, but either webmail doesn't work, forwarding doesn't work, or all emails from the server end up in the spam folder. Marc has been helping me, since he has control of the DNS, but I don't want to bother him too much if it's not a priority for him. I'm wondering if anyone who is experienced with email and/or DNS wants to hack on this email server with me, maybe Tuesday before or during the meeting. If nobody is interested, I'll probably drop it for now and we can keep using personal email addresses. -Jehan