Endpoint Encryption

I am using PGP Desktop 10.1.1 and it always encryptes e-mail, when it finds a PGP-key of the people I want to sent the mail to.
I am using Outlook 2007 with an Exchange-server.
I have configured PGP Desktop via Options->Messaging-> secure e-mail and have set " activate PGP-encryption Button ... in Outlook".
But it does not matter, if I set the "Encryption" button when creating a new email, or not, the emails are always encrypted.

How can I choose the emails to encrypt and those which shall not be encrypted?

Thanks for any advice!

In PGP Desktop, click on the PGP Messaging module on the left, click Edit Policies on the right, remove the check for the Opportunistic Policy, click the Done button on the right.

Thanks, this has worked!

Very glad to hear this is resolved!  I would appreciate it if you use the Mark As Solution option on my post providing the solution.