Some of the email clients that looked like a solid alternative to me (Spark, Polymail, Mailspring) use a backend that store the IMAP credentials. To me, this looks like a additional security risk. I run a small software company and if a third party gains access to my emails (and even send emails from my account), they could cause significant damage.
How do you assess these risks? Do you trust these email clients? Which clients do you use?
Here's a no-BS email client that doesn't have this issue: https://freron.com