[bug-anubis] How to check for existing header

[Bob Kromonos Achten]

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How do I check, if i.e. header[Content-Type] exists?
I tried with:

if (header[Content-Type] "^text/plain;.*" or header[Content-Type] "") \
        and not header[X-GPG-Comment] :posix "Encrypted for (.*)"
                add body "Test"
fi


But seems not working :(
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