After getting fed up with ProtonMail recently I went on a quest to find an alternative. Unfortunately Skiff doesn't have SMTP or even an export feature so once you go Skiff you can't go back, you're locked in.
ProtonMail does have import/export and the SMTP bridge (for paid users) and those things work but ProtonMail mangles emails: it removes plaintext body where there's a HTML body and it screws with headers.
Ultimately the best option I could come up with was self-hosting my email address. Incoming emails go directly to a box sitting in my office, with TLS enforced.
I put this off for years fearing deliverability issues but finally realised that incoming and outgoing email can be hosted in different places. So though the box in my office receives my email, I send email through either a Hetzner box or Mailgun (with retention disabled). Haven't encountered any issues with this so far.
ProtonMail does have import/export and the SMTP bridge (for paid users) and those things work but ProtonMail mangles emails: it removes plaintext body where there's a HTML body and it screws with headers.
Ultimately the best option I could come up with was self-hosting my email address. Incoming emails go directly to a box sitting in my office, with TLS enforced.
I put this off for years fearing deliverability issues but finally realised that incoming and outgoing email can be hosted in different places. So though the box in my office receives my email, I send email through either a Hetzner box or Mailgun (with retention disabled). Haven't encountered any issues with this so far.