Just wondering if the email was a generic one that is sent to everyone, even if you have already sent all the info or if it's case specific?
I ask this because we sent bank statements, joint bank statements, my girlfriends T4 slips, copy of her UK 2 year work permit, as well as police cert, medical and the payment with the original application. These are the things that were in the email so it wasn't clear if it's an email to say
"this is what your application should include and so if you have not sent any one of these yet, send it now."
Or they are asking you to find and send more info even if you have already submitted them.