Email, as a decentralized and resilient platform to exchange messages, is highly regarded and I wouldn't trade it for anything else.
However email, as a platform to exchange secure messages, is total stinking crap.
§ Who use emails anymore?
I do! And since is very important communication medium for me, I want to take advantage of all the flexibility possible from this tool, so I manage two email servers (one being decommissioned) with POP3, SMTP and IMAP. But emails were not meant to be secure. And also not meant to be abused.
Today, in order to have the slightest chance to get your emails through and reach their destination, you need to configure DMARC, DKIM, SPF records to be trustworthy.
Then you want to have everything under SSL, so you add certificates and move everything to POP3S, IMAPS, SMTPS.
And yet, all that won't be enough because you might happen to be on a IP address block with a "bad reputation", spamlists will blacklist it and incidentally also you that happen to be caught in the net. Google and other email providers will refuse your emails even if you damned your soul to configure and test all the latest "best practices".
§ "crowdsourcing" a mail server reputation
Google and Microsoft/Office365 servers are famous for giving headaches when receiving your emails, here are examples of stories from sysadmins having to cope with Microsoft services (here and here) and Google and the "cargo cult" countermeasures they implement to have their servers not blacklisted.
The reason this happens is that Google and Office365 implement opaque heuristics to assign and revoke trust to all the other mail servers. They don't share the details of these rules to not lose the advantage over the bad guys.
What happens in reality is that they whitelist themselves (gmail, outlook) at the expense of all other legit mail servers. Head counting how many people talk good about my mail server is just plain wrong.
Their reasoning is to build up a good reputation. But a small mail server won't contact enough recipients and doesn't send enough emails to build up a reputation.
There are other valid options to ensure mail servers are not spammers: DKIM and DMARC are there for a reason, for example. I am fully in favor to punishing email providers that do not adhere to the best practices and flag them as untrustworthy.
I also find that I cannot set my Postfix mail server to only talk through encrypted connections (
smtp_tls_security_level=encrypt) because many servers do not support it and refuse my connections, so I see on the other hand a problem of infrastructure moving slowly to implement said best practices.
§ they're not bad: extreme problems requires extreme countermeasures
And also, most part of emails circulating are spam.
Yes, I know.
If you are that big, you are also responsible for not breaking the ecosystem. Big companies must be accountable of the side effects of driving the steamroller and taking down everything. By doing so they've just set themselves above from the rest (my big service works, suck it down, small provider).
§ So you want to send encrypted emails?
To who? The whole workflow to setup a GPG key and configure an offline email client is clumsy, that's not a surprise that nobody sends encrypted emails. There are praiseworthy projects trying to overcome this, such as autocrypt and delta.chat, but the first is implemented only by a fistful of email clients (all of them are F/LOSS projects), the latter is in a much bigger arena, where it's hard to get noticed.
This is why most people use a cloud service for emails: I also use one, they've done a good job at hiding all the gory details and simply make encrypted email work, but the bottom point is that unfortunately I can't trust my own mail server for work-related purposes with so many people on gmail.