In Postmypost, go to the Accounts section and click Connect.
In the window listing social networks, click Connect next to Reddit.
A window will open for officially connecting your Reddit account to Postmypost, detailing the specific data and permissions Postmypost requires. Ensure you agree to grant access and click Connect.
After successful connection, you will automatically return to Postmypost, where a list of available accounts for connection will open. Check the box next to the desired accounts and click Connect.