Enum EmailSearchRetrievalMode

Namespace

MailFathom.Application.Emails.Search

Assembly

MailFathom.Application.dll

How a search found and ordered what it returned.

public enum EmailSearchRetrievalMode

Fields

Hybrid = 1

Matched by full-text ranking and by vector similarity, with the two orderings combined by Reciprocal Rank Fusion.

A message can rank here without carrying any of the query's words, and one that carries them exactly still ranks near the top; what neither ordering found is absent from both.

Lexical = 0

Matched and ordered by full-text ranking over the words the mail is written in.

A word the query does not contain finds nothing, however close its meaning: no vector took part in this ordering.

Remarks

It is part of the result rather than a property of the deployment, because the answer can differ between two searches of one instance: an embedding provider that is unreachable for the length of one call leaves that call lexical while the instance stays configured for hybrid retrieval. A caller reading the mode reads what happened to its own query.