Sylpheed and GnuPG / OpenPGP

Is there a tutorial how to integrate GnuPG in Sylpheed portable?

What I tried:
Installation of Gpg4Win (perhaps a problem, because it is not Portable).

Edit the \App\AppInfo\Launcher\SylpheedPortable.ini, added

[Activate]
Registry=true

[RegistryKeys]
GnuPG=HKEY_LOCAL_MACHINE\SOFTWARE\GNU\GnuPG

Create \Data\settings\GnuPG.reg with:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\GNU\GnuPG]
"Install Directory"="C:\\Program Files (x86)\\GnuPG"
"gpgProgram"="C:\\Program Files (x86)\\GnuPG\\bin\\gpg.exe"

But the message "GnuPG is not installed properly, or its version is too old." is still there

Thanks for any help.