All email services selling encrypted email as a service are snake oil in my opinion. You won't gain anything more than when using GPG by yourself, except you'r

All email services selling encrypted email as a service are snake oil in my opinion. You won't gain anything more than when using GPG by yourself, except you're now trusting a third-party app to do it for you, using a non-standard adapter for allowing IMAP / SMTP apps to still work while at the same time obscuring the fact that end-to-end encryption will only happen when the recipients support it as well, which is at most 1% of all recipients you're communicating with.