Just curious. . . for those of you who use a secure/encrypted email provider, do you do so because you actually send sensitive and/or confidential content -- or just because you like the idea of privacy?
If I had such an email, I would only use it for sending confidential information that I don't want anyone else to know. But since I keep those to myself or by word of mouth to those I trust, I don't really have a need for one.
Ironically, regarding the content, you are better legally protected making regular phone calls in most jurisdictions (officially, though not cross jurisdiction), than you are with unprotected emails (which are like postcards that are algorithmically scanned and stored for ages - not normally by humans so it doesn't count honest). Of course, metadata is another thing, and email services vary on that.
Convenience, compatibility, (work) requirements, (more than just email) syncing, overall familiarity, (social) acceptance, etc.
Although I have a few accounts at "secure email" providers, I do my own end-to-end encryption. Typically I use Thunderbird or Icedove with Enigmail and GnuPG. Sometimes I use webmail, and encrypt/decrypt manually with GnuPG. But anyway, I just use plain-vanilla privacy-friendly email providers. Riseup, obviously. Also VFEmail and a few others. Edit: To answer TomAZ's question, for Mirimir and other pseudonyms, I use GnuPG whenever possible for non-list email. Sometimes, there is content that needs to stay private, such as account and server credentials, financial information, and so on. But mostly it's just a matter of principle. Still, it's not like I expect anything to stay "secret", because I give up control of anything that leaves my devices. But I do not share private information from one person with other people without first getting permission. That is, I don't gossip. And I expect that from others. It's a respect thing.
Other than my secret pulled pork recipe not too much that is sensitive. Mainly use pgp for my server and download notices.
If I could represent my view of business-2-business communication and at rest, I think that businesses should be required to encrypt by default, to fulfil their data protection responsibilities as well as their fiduciary duties to their shareholders. The reasons are obvious. But, to the contrary, they are allowed to get away with really dire behaviour. I have a particular reason to be unhappy with the behaviour of the TLAs, namely that I have communicated intellectual property with my patent agent/lawyers within-country, and although some content was encrypted, not all was, nor is it that easy to handle the metadata. Yet, as the Snowden revelations have shown, not only is this monitored by my own country's spooks, they gleefully pass it on to many other countries and hence exposure to economic espionage. I think I have a reasonable expectation that that communication was private, unless they have very strong reasons which would have to be individually warranted. I'll leave to one side what I think of their behaviour, but just say that I am strongly motivated never to trust them again - they have broken the unspoken contract.
It's not uncommon for hosting providers to provide root passwords via plaintext email. Some VPN providers send usernames and passwords that way too. That's insane!