Step 1: Create the lead templates in the agency account

Create lead notification templates in your agency account under Assets => Email Template Library.  You can base your template off of our lead templates which will all be available under System Email Library when creating your new template.

Once you are done creating your template, make sure you set the brand to be the brand you want your clients to see when the lead is set.  Also change the From/Reply to information to use the brand account like this:

Make sure that "Template is visible to sub accounts?" is checked:

Step 2: Link to the lead templates in the client account

Next go into the Lead Processing Workflow in your client account.  You will need to create a new "Email Sales" workflow action at the point in the workflow where you want to send the lead to your client:

One you drop the action on the workflow, click the "New Email" button.  Look under the "System Email Library" accordion.  Your lead template you created in Step 1 will be listed there towards the bottom.  Click your template, and then click the "Link Template" button:

You can now save your workflow and test it.  The lead email will be branded with your agency brand, and will come from your agency email address.