It depends on the people I guess. Some managers will be annoyed of such conversations when they have to approve payments like that on multiple occasions a day -

It depends on the people I guess. Some managers will be annoyed of such conversations when they have to approve payments like that on multiple occasions a day - so employees might want to avoid such conversations. The attacker could even add something like that: "I am currently on a trip. If you are unsure call me on my private mobile phone number..." and then respond with a faked voice. I think a good way of reaching targets would be a "double" forward. So the sender assumes the role of an employee forwarding the email of a manager to an administration adjacent employee. This employee unsuspectingly forwards the seemingly harmless mail (that seems to be forwarded from the manager) again for a reason like birthday wishes or sick notice. This will make it hard for the actual target to understand where the email originally comes from. Beside that one can easily think up more creative ways to use this "feature". E.g. letting unsuspecting persons forward problematic content and then blackmail them etc.