BlackBerry Storm2 9550

I setup a gmail account and then setup my work email in the settings -> accounts and import. The reply is setup to use works email, but for some reason if someone attached a delivery receipt in outlook both the works ISP and gmail send delivery receipt emails. The issue is that the gmail account sends the delivery email using the gmail account.

I don't want our customers knowing my gmail account.

This issue does not happen with the Droid Gmail App.