+# This subject rewrite is embedded in double-quoted strings. As such, some of
+# the items need more escaping than usual, otherwise \N becomes simply "N" and
+# the following "\[" a literal "[".
+# Note that the lack of space in "Subject:${" is intentional, as the raw Subject
+# header will include the leading space, if present.
+RT_SUBJECT = Subject:${if and {{first_delivery}{match {${sg {$rh_Subject:}{\\n([ \\t])}{ }}}{\\N(?i)(.*?)\\[?debian rt\\]?[:\\t ]*(.*)\\N}}}{$1$2}{$h_subject:}}