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Searching with Notmuch

What good is an advanced indexing mail client if we don't know how to use it to actually find e-mail?

The notmuch-search-terms manual page should cover everything in a fairly concise manner. Please refer to that for any details.

Notmuch uses the Xapian search engine. The Xapian QueryParser documentation has a generic description of the search language. The intended audience is developers wanting to use Xapian in their applications; this page attempts to explain it to users of Notmuch.

Stemming

See the Wikipedia article for the detailed description. What this means for us is that these searches

    notmuch search detailed
    notmuch search details
    notmuch search detail

will all return identical results, because Xapian first "reduces" the term to the common stem (here 'detail') and then performs the search.

The only way to turn this off is the so called search for proper names: a search for a capitalized word will be performed unstemmed, so that one can search for "John" and not get results for "Johnson".

Languages other than English

Stemming is currently only supported for English. Words in other languages will be performed unstemmed unless somebody teaches Xapian how to perform stemming for that language.

Synonyms

(how is the QueryParser configured?)

Wildcards

It is possible to use a trailing '*' as a wildcard. A search for 'wildc*' will match 'wildcard', 'wildcat', etc.

Operators

Xapian implements the usual operators and a few more that are useful when searching e-mails.

Note: The operators need not be capitalized for notmuch, so 'NOT' and 'not' are equivalent. The capitalized form is used below only for readability

'+' and '-'

    notmuch search +term1

will only return results that contain 'term1'.

    notmuch search -term2

will return results that do not contain 'term2'. '+' and '-' can also be used on bracketed expressions or phrases (see below).

AND and NOT

notmuch search term1 AND term2

will return results that contain both 'term1' and 'term2'.

If no explicit operator is provided all search terms are connected by an implicit AND, so these two searches:

    notmuch search term1 AND term2
    notmuch search term1 term2

are equivalent.

    notmuch search term1 NOT term2

will return results that contain 'term1' but do not contain 'term2'. For a query that looks more like natural language you can also use AND NOT

    notmuch search term1 AND NOT term2

XOR (exclusive OR)

    notmuch search term1 XOR term2

will return results that contain either 'term1' or 'term2', but not both.

OR

    notmuch search term1 OR term2

will return results that contain either 'term1' or 'term2'.

Brackets

Operators above are listed in the default order of precedence. One can override the precedence using bracketed expressions:

    notmuch search term1 AND term2 OR term3

is the same as

    notmuch search (term1 AND term2) OR term3

but not the same as

    notmuch search term1 AND (term2 OR term3)

NEAR

    notmuch search term1 NEAR term2

will return results where term1 is within 10 words of term2. The threshold can be set like this:

    notmuch search term1 NEAR/2 term2

ADJ (adjacent)

    notmuch search term1 ADJ term2

will return results where term1 is within 10 words of term2, but in the same order as in the query. The threshold can be set the same as with NEAR:

    notmuch search term1 ADJ/7 term2

Phrases

According to the Xapian documentation a phrase surrounded with double quotes (like this: "my phrase") will return results that match everything containing "that exact phrase", but hyphenated words or e-mail addresses are also treated as phrases.

In practice this means that these two searches are not equivalent:

    notmuch search "Debian Project"
    notmuch search Debian ADJ/1 Project

Prefix searches

You can search your collection by using several prefixes, like this:

    notmuch search from:john

This will return results where 'john' appears in the name or the e-mail address. See 'notmuch help search-terms' for a complete list of prefixes.

Message IDs

An important concept for notmuch is the Message-Id, which is a unique identifier for each message. Individual messages can be accessed via their message ID with the "id:" prefix:

    notmuch search id:<message-id>

Range searches

Since notmuch is about (large) e-mail collections it is very useful to be able to search for e-mails within a specific date range. This will work:

    notmuch search date:<since>..<until>

For <since> and <until>, notmuch understands a variety of standard and natural ways of expressing dates and times, both in absolute terms ("2012-10-24") and in relative terms ("yesterday"). Please refer to the notmuch-search-terms manual page for details.