Consider performing a
SpamAssassin Rule: DATE_IN_FUTURE_96_XX
Standard description: Date: is 96 hours or more after Received: date
Explanation
The Date header is normally set to the date that a message was created. In this case, this date is more than 4 days later than the message was received, suggesting that either the message was generated by badly-written mailout software, or the sender's computer clock is very wrong.
Further Info
The default scores for this rule can be found in the online list of tests.