I've run a lot of self hosted email and still do. For 25 years or so, for many SMEs and personally. The "Thou shalt not run thine own MX" meme is bollocks or

I've run a lot of self hosted email and still do. For 25 years or so, for many SMEs and personally. The "Thou shalt not run thine own MX" meme is bollocks or at least needs some qualification. If you let S&M loose from your main domain with spam then you will quickly vanish. If you have an IP that belongs to a consumer ISP then you will need to do some initial "polishing", which will probably start at Spamhaus. In my experience, if you keep Spamhaus on side then most email systems will give you a fair look. Get the basics right - (E)HELO => DNS (A and PTR) and SPF with -all on the end. Ideally your SPF should be "mx -all" which means you send and receive email on one small set of gateway systems, with no includes which implies marketing mail. That's why you should spam errrr market from another domain or a sub domain. Use Mail Pig or whatever to do your dirty work - that's what they do. Depending on where in the world you are, then your IP will accrue some reputation - good or bad. Sorry can't help there but a VPN or a remote VPS might sort that out. There's a bit more to it than the above but that gets you started. Anti spam systems are not psychotic and don't hate self hosted setups. Even the big jobbies have to still give the benefit of the doubt to a sender but they have a huge rule set of heuristics and a twinge here and a poke there might cause you to vanish. It's all about scores and scoring points. Avoid scoring points and you will be fine. My MTA of choice these days is Exim with rspamd. rspamd has a great symbols to points system where a symbol might be RDNS_IS_BOLLOCKS and the score for that symbol might be +1.5. You can fiddle with scores in the web interface so you can override the defaults quickly and easily. You might decide that SENDER_DOMAIN_DOT_RU gets +10. I've made up my example symbols for this post but you can make up your own like these in the system quite easily. Anyway. There are rules for running email systems and if you follow them, you will probably be fine.