There is a reason why almost nobody self host an email server these days and it's that while it's relatively easy to set up it's pain in the a to maintain. Not only the handling and upkeeping of spam filterings and blacklist a random mail server tends to get black listed with the big players like google and microsoft which are biggest players on the email services these days. Internet used to be full of small and even free email services long time ago but one by one the number seems to go down.
One of the biggest challenges for a service provider is managing trust with your own customers, and complying with an ever increasing rule book on how to do it
In a private server this is one issue less because you yourself are the customer. You have to manage the actual security (encryption, sysadmin) and external registrations (domain and certificates), but there are much less unanswered questions there
(I am currently an owner of a registered domain name, but not of a personal email server)
In the case of email the requirements to be whitelisted are openly explained :
https://www.cloudflare.com/learning/dns/dns-records/dns-spf-record/https://www.cloudflare.com/learning/dns/dns-records/dns-dkim-record/https://www.cloudflare.com/learning/dns/dns-records/dns-dmarc-record/As long as the actual check is "This is Ash who owns the domain, and not a 3rd party bad guy pretending to be Ash", not "This is Google, and not Ash who is just Ash", this works as expected...
I have checked (in private) with a sysadmin friend who maintains servers in businesses before posting this comment. The ones who still have a web server of their own (he is a Microsoft guy, so his clients tend to be on Exchange), generally send and receive emails correctly with anyone else as long as they have the above 3 records
He also confirms that private email servers are on the decline, but i (ash) think this is more consequence of a general pushing of everything to the cloud (including all licenses, office, CRMs, you name it), less anything to do in particular with email
Would not put it past the big players to also give preferential treatment to their (and each others) webmail or cloud mail service vs. a private server, or to Exchange vs. some free software email server, all other variables equal. But i conclude from the discussion that this is not a thing, or at least not huge
I don't call for mass migration...
I call for you to join the unrestricted services if you want to communicate with me online, because i'm not joining the restricted ones to communicate with you
Whether you do or don't keep your other online accounts is none of my business