Indexing Message-ID header

Questions
1

Your question

How do I configure a non-text mail header like Message-ID to be indexed?

2

Let me look into how Stalwart handles header indexing configuration.

The headers field value in indexEmailFields is what you need. The SearchEmailField enum includes a headers option (“Email Headers”) which is not enabled in the default list.

The default indexEmailFields list is:

["from","to","cc","bcc","subject","body","attachment","receivedAt","sentAt","size","hasAttachment"]

Notice headers is absent. To index Message-ID (and all other email headers), add "headers" to the indexEmailFields list in the Search object. You can find this in the WebUI under Settings > Search. Once headers is included, all headers - including Message-ID - will be included in the full-text index.

Keep in mind:

  • This will apply to all headers, not just Message-ID - there is no per-header granularity exposed in this configuration.
  • After changing the setting, you may need to re-index existing mail for the change to apply to existing messages (check the Tasks/Actions section of the WebUI for a re-index task).

Reference: Search Store docs and the Search object reference.

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