Glad to hear Marco follows the same logic as I do: In a response to this post by Siegler:
For something as important as email, I’ve never trusted everything to a proprietary provider. My email address has never ended in someone else’s domain name, and has never been hosted in any way that would preclude me from easily switching to another provider.
Since 2007, I’ve used FastMail, a paid IMAP host, for my @marco.org email addresses (with the $40/year “Enhanced” personal plan). Rather than using its (unsophisticated) web interface, I use Apple’s Mail app.
FastMail’s uptime has been incredibly good — I don’t remember the last time I saw any downtime, but I’m sure that the total downtime I’ve ever seen from them has been less than an hour. But if it ever starts to suck, it’s just IMAP, and I own the domain, so I can switch to any other IMAP host easily (or self-host it, which I don’t recommend, but it’s always an option).1
All of my messages are downloaded by Mail and stored as files locally, so if a data-loss disaster were to happen at FastMail (which can happen to any service, even Google’s), I can recover my email from my personal backups.
You must own any data that’s irreplaceable to you.
By relying on a hosted service with no direct alternatives or difficult outbound migrations, you’re giving up a level of control that you shouldn’t for something as important as your business email.
I have never relied solely on one cloud based service even if I’m paying for it.