Identify mails that send directly from maiser 4.8

In Mercury 4.7x  a "Sender" field was added to every E-Mail, that was sent from  the Mercury listserver.
Thismeant thatalways"Maiserinorder of ..."has been displayedineachemail,butalloweda clear identificationtoavoid multipleprocessing.

InMercury4.8, this field isnotsetandwe need for ourpolicies(scripts)another option now.
Could we usethe field "X-listname"anddelete them afterprocessing?How does it affectif wedelete this fieldduring the processingofe-mail?

Operation:
Weuse theMercury listserver as our projectserver.Each listcorresponds toaconstruction project.
Just ourpart of thecommunication is done viathe server,which is why our users have to know whothe emailoriginallyget even.
We usethePolicyCMDscriptswithFindand especially Sed to modify the e-mails and allow this. 

Thanks, Torsten