HEADER finding

Missing List-Unsubscribe header

The message has no List-Unsubscribe header. For bulk senders, Google and Yahoo require it since February 2024.

Finding code

missing_list_unsubscribe

This finding appears in the findings array of the spam checker and the POST /v1/sender API response when the condition above is detected.

How to fix it

The fix.

Add List-Unsubscribe and List-Unsubscribe-Post headers to bulk and marketing messages. Google and Yahoo require them for senders above 5000 messages per day, and their absence increases the chance of landing in spam.

Related HEADER findings

Other things we check.

Finding What it means
no_authentication_results No Authentication-Results header
missing_message_id Missing Message-ID header
missing_date_header Missing Date header