Custom Scanner + Adding Header

[Daniel]

Hi everyone,

I have been trying to find a documentation about adding custom scanners 
to Amavis-new, which themselves can add headers to the mail or instruct 
Amavis to do so.

My questions would be:
How is my custom scanner supposed to behave in order for amavis to:
a) recognize it
b) capture its output
c) add a custom header to the mail, that I can define

Is this even possible?