No offense but unless it’s a 1st party client email clients are something that is very hard to trust.
This seems an odd position to me.
Online clients are well known to be scanning your emails, necessarily involve giving access and control to third parties, are impossible to use while retaining control of private encryption keys, and so on.
Local clients might have some of those problems. If they're open source then in theory you could audit them and find out, but in practice even that gives a false sense of security because no-one has the resources and willingness to undertake that work every time they install a new version.
Ultimately software security is still all about who you trust, the same as always.
This seems an odd position to me.
Online clients are well known to be scanning your emails, necessarily involve giving access and control to third parties, are impossible to use while retaining control of private encryption keys, and so on.
Local clients might have some of those problems. If they're open source then in theory you could audit them and find out, but in practice even that gives a false sense of security because no-one has the resources and willingness to undertake that work every time they install a new version.
Ultimately software security is still all about who you trust, the same as always.