Best email app for iMac?

[ElectronGuru]

Mailsmith appears to be spun off (from the BBEdit people), but it was pretty hard core in its day:

http://www.mailsmith.org/

 

[Huntn]

Mailsmith appears to be spun off (from the BBEdit people), but it was pretty hard core in its day:

http://www.mailsmith.org/

Any idea of what compatibility it has with gmail and gmail labels/filters? I'll go check it out too. Thanks