Regexps that accept exactly one the year in the Date: field will bounce some email around the end of the year, because year changes don't happen globally at the same time, and email may be in transit for up to a few days.
By the end of 2019 the patterns should be: /^Date: .* 2019/ DUNNO /^Date: .* 2020/ DUNNO /^Date: .* [0-9][0-9][0-9][0-9]/ REJECT bad year in date And by the end of 2020: /^Date: .* 2020/ DUNNO /^Date: .* 2021/ DUNNO /^Date: .* [0-9][0-9][0-9][0-9]/ REJECT bad year in date This could be automated by a cronjob. Wietse