I was/am contemplating ProtonMail from Fastmail. I've been using it for a couple years now and it's been awesome. I was hoping to gain additional security with

I was/am contemplating ProtonMail from Fastmail. I've been using it for a couple years now and it's been awesome. I was hoping to gain additional security with ProtonMail but maintain the flexibility I need with multiple accounts and shared addresses that Fastmail does very well.