Following are the steps that you can take to export your OpenPGP keypair from eM Client.
1. Go to Menu -> Settings.
2. Go to Signing and Encryption -> Certificates and Keys and double-click on the keypair to export.
- Make sure that My certificates/keys tab is selected.
3. Click on Export -> Export PGP keypair….
If you still face issues in exporting your OpenPGP keypair from eM Client, then send us an email to firstname.lastname@example.org (PGP key).