Login details emailed everytime I add a new user to a projec

Login details emailed everytime I add a new user to a projec

Is there anyway to turn this option off? Everytime I add a new user to a project, it emails them login information. While this may be a useful feature for some, it's not for my project team! We get enough emails as is.

Can anyone give me any answers on this?
Ashley Lichty