notmuch 0.21-3ubuntu2 (arm64 binary) in ubuntu xenial

 Notmuch is a system for indexing, searching, reading, and tagging
 large collections of email messages in maildir or mh format. It uses
 the Xapian library to provide fast, full-text search with a very
 convenient search syntax.
 .
 This package contains the notmuch command-line interface