When first discussing it with the client, my initial thoughts were to use a macro to enable merged from the supplier list to step through the vendors/creditors and enable that way.
However, just before I started to explain this, I remembered a feature tucked away on the Vendors/Creditors navigation list. If you click the button, in the Modify section of the area pane, of two chevrons pointing to the right you get a pop-up menu containing an Email Settings option:
Clicking this option will open the Mass Vendor E-mail Settings window.
In this window you can choose your email options such as the Attachment Options, Send Form as E-mail options (where you can choose which documents can be emailed and the Message ID and Format for each document type:
Once you’re happy with your entries, click OK and the settings will be applied to all of the vendors/creditors marked in the navigation list.
There is similar functionality available for the Customers/Debtors in Receivables Management as well.