Openmailbox 2.0: new owner, outages, paywalled and removed features

Not to blame the victims, but assuming this was a free service to begin with, why did you trust it in the first place? Something bad was bound to happen as nobody will just give you their time and bandwidth for free forever.

By the way, a Exchange Online Kiosk subscription (mail only, no Office) on Office 365 is only about 2£ per month. You've also got FastMail but I think they're slightly more expensive.