Open a Write window Turn on the Contact Sidebar if not already on. Press F9 to turn on Select a group of contacts and use the Add to BCC button at the bottom of the sidebar BCC = Blind Carbon Copy = does not reveal email addresses in the received email

You may have to do this in small groups depending on if your provider limits how big of group mail you can send and how big your address book is.

You use standard computer selection methods to select more than one contact.

control+a = select all

click one contact to select it, move down several contacts and hold the control key while clicking a second contact = select both contacts clicked on and all in between

hold the control key while randomly clicking contacts = select any contact clicked on

hold the control key while clicking a selected contact = deselect that contact

Thanx