OPNSense, Sensei and Mail in a Box

[ursus]

Hi Guys. I have just installed a new OPNSense FW, I have a Mail-in-a-Box instance running in my DMZ. I am using port forwarding to the Mail-in-a-Box server for mail for a couple of my friends and myself. I thought that I would try and install Sensei and am very impressed with it - well done guys. I monitored both the LAN and the DMZ interface. I left everything activated in Sensei but am getting very weird errors from Mail-in-a-Box. It is now saying port 22 cannot be reached, I cannot send and receive mails correctly, the box cannot update (apt update) itself anymore. I have had to uninstall Sensei again for everything to go back to normal.

What can I do to still use Sensei *and* Mail-in-a-box? Any pointers?

Thank you in advance
Ursus