How do I send a group email?
To send invitations, solicitations, invoices, receipts, thank yous in bulk, use the "Actions on Bidders/Donors" menus found at the bottoms of the Patrons > Bidders > Manage and Patrons > Donors > Manage lists respectively.
ReadySetAuction is not a general email application. For general email functionality, export your donors and/or bidders to Excel (Reports > Data Exchange Reports) and then import to a mail specific application like Mail Chimp or Constant Contact.