From: DeskNow Knowledge Base

I cannot send encrypted emails. The InternalError log says: java.lang.SecurityException: Unsupported keysize or algorithm parameters

This error means that you need to install - as recommended in the installation instructions - the encryption policy files that enable Java to use export-controlled encryption algorhitms. This error normally does not occur if you installed DeskNow on Windows using DeskNow.exe, as it already includes these files.

See for installation instructions.