While a similar way of using email can be achieved in other mail clients [0] the simplicity of having such features by default it's by itself a good reason.
Some features that are non-trivial to emulate in other email clients are:
- Grouping emails with different subjects etc to the same
- Adding private notes is some emails
- Clipping specific parts
- Some UI specific features (Focus & Reply etc.)
[0] https://klinger.io/post/71640845938/dont-drown-in-email-how-...
I've submitted four "hi this is just a feature request, no action needed" tickets to FastMail over the four years I've been a customer. Every time, a person who appeared to have a clue (based on their responses) replied to me with at least confirmation of "sure, we'll think about it, might be a heavy lift" and they did two of them.
So I have a few Frankenstein's Monster accounts where I log in with something obsolete but get contacted to a current email address.
That's crazy. People change email address sometimes. Surely no major service actually does this?
Your old gmail account will linger, but soon, it will be relegated to spam and near-spam.