SpamAssassin rule
INVALID_DATE
Invalid Date header
+0.432 points
Header test
What INVALID_DATE means
The Date header is not in the format the email standard requires.
The rule's description in SpamAssassin: “Invalid Date: header (not RFC 2822)”
How to fix it
Use the RFC 5322 format, e.g. Thu, 01 Oct 2026 15:50:00 +0000. Most libraries have a helper for this.
Does your email trigger INVALID_DATE?
Send it to a free test address: we run SpamAssassin, check SPF, DKIM and DMARC and show every rule with a fix.
Open the email spam checkerRelated rules
FROM_EXCESS_BASE64From header needlessly encoded
MAILING_LIST_MULTILooks like mailing-list software
MISSING_DATENo Date header
MISSING_FROMNo From header
MISSING_HEADERSNo To header
MISSING_MIDNo Message-ID header
MISSING_SUBJECTNo subject
MSGID_FROM_MTA_HEADERMessage-ID added by a relay
REPLYTO_WITHOUT_TO_CCReply-To but no To or Cc
Frequently asked questions
What does INVALID_DATE mean?
The Date header is not in the format the email standard requires.
How do I fix INVALID_DATE?
Use the RFC 5322 format, e.g. Thu, 01 Oct 2026 15:50:00 +0000. Most libraries have a helper for this.
How many points does INVALID_DATE add?
0.432 points in the default SpamAssassin ruleset (network tests on, Bayes off). A message is treated as spam from 5.0 points. Mail servers can change scores locally.