I want a "Mail-in-a-box"/Plex mashup... that lets self hosters setup a domain, with a mail server than handles all the spam and "trust" shit that comes with hos

I want a "Mail-in-a-box"/Plex mashup... that lets self hosters setup a domain, with a mail server than handles all the spam and "trust" shit that comes with hosting a mail server. The new hosting service does all the trust and anti spam/virus/phishing stuff, and maybe does or helps with the neat stuff you get from gmail (indexing and clever integration to calendar and travel/shipping integrations.) We'll either buy VPS or self host on hardware in our house the actual data.