How to inject disclaimer of "From"-Mail when Sender is different with a Mail-Flow-Rule

Hey guys,

I'm currently trying to define a Mail-Flow-Rule which checks whether an E-Mail was sent from someone who has the permission to write a mail as a delegate.
E.g.:
We have two users: Chief and Sub
Sub is a substitute of Chief
Sub writes an E-Mail for Chief
=> The E-Mail header "From" is Sub while the "Sender" Header is Chief

The check works fine, but I cannot include specific AD Properties from Chief into the Mail.

When using for example %%Email%%, the Mail-Adress from Sub is injected into the disclaimer.

My questions:
- Is there a way to get specific Informations about Chief?

- Is there another feature aside from "Mail Flow Rules" which allows this?