# Sieve filter
if header :matches "x-special1" "*\0*" { discard; }
==========
-No implicit keep
+Implicit keep
==========
# Sieve filter
if not header :matches "x-special1" "*\0*q" { discard; }
No implicit keep
==========
# Sieve filter
+require "encoded-character";
+if not header :matches "x-special1" "*${hex:00}*" { discard; }
+==========
+Implicit keep
+==========
+# Sieve filter
if not header :matches "x-special2" "\\?*\\*" { discard; }
==========
No implicit keep