SIEVE question

[Ralf Haferkamp]

Hi,

Is it possible to write a SIEVE filterrule that checks all mail headers for
a specific string? Something like:

    if header :contains [*] "blahblah"{
        discard;         ^
    }                    |
                         |
                         |___________________________
                          What do I have do put here to 
                          test _all_ mail headers?
-- 
regards,
    Ralf