One of my users is using a mac to connect to a Windows remote terminal. When trying to enter email addresses the @ symbol on the mac is typing a " symbol.
Which key on the mac will type an @ symbol into the remote terminal?
It entirely depends on their keyboard layout. Note that there are several different hardware keyboard layouts, as well as software keyboard layouts that can be selected by the user. This character can be in many different locations on the keyboard depending on the layout.
The keyboard layout can be viewed by enabling the viewer menu item in
System Preferences > Keyboard > Keyboard > Show Keyboard … Viewers in menu bar
and then choosing Show Keyboard Viewer in the input-method system menu.
Once the keyboard viewer is visible, press the various modifier keys like Shift ⇧ to discover what key(s) are needed to type the “@” symbol.