SpamAssassin Rule: FH_DATE_PAST_20XX
Standard description: The date is grossly in the future.
Explanation
The rule matches the year (a string of four numbers) in the Date header, and checks if it is between 2010 and 2099.
Further Info
The default scores for this rule can be found in the online list of tests.
Note: the current rule in 3.2 will start matching legitimate dates from 2010-01-01. See issue #5852.