I've been using Thunderbird for years but had problems transferring my accounts to it on my most recent Sparky installation (Minimal Gui Rolling) and am using Seamonkey instead, which lacks some of add-ons I use.
The Sparky-APTus-App-Center facilitates installing quite a few email clients but I'm not familiar with many of the ones shown so I'm asking for recommendations of a graphic (not command line) email client app that does imap, is full featured but fast and combines well with Openbox.
TIA
The only other email client I trust is Evolution.
However, I've been moving Tbird around since forever without any problem, so maybe you could explain in more detail the issues you had?
I've run mailspring for 6 or so months.
Evolution