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+=head1 NAME
+
+lei - an overview of lei
+
+=head1 DESCRIPTION
+
+L<lei(1)> is a local email interface for public-inbox and personal mail.
+This document provides some basic examples.
+
+=head1 LEI STORE
+
+lei has writable local storage based on L<public-inbox-v2-format(5)>.
+Commands will automatically initialize the store behind the scenes if
+needed, but you can call L<lei-init(1)> directly if you want to use a
+store location other than the default C<$XDG_DATA_HOME/lei/store>.
+
+The L<lei-import(1)> command provides the primary interface for
+importing messages into the local storage.  In addition, other
+commands, such as L<lei-q(1)> and L<lei-blob(1)>, use the local store
+to memoize messages from remotes.
+
+=head2 EXAMPLES
+
+=over
+
+=item $ lei import mboxrd:t.mbox.gz
+
+Import the messages from a gzipped mboxrd into the local storage.
+
+=item $ lei blob 59ec517f9
+
+Show message with the git blob OID of 59ec517f9.  If a message with
+that OID isn't found, check if the current git repository has the
+blob, trying to reconstruct it from a message if needed.
+
+=item $ lei blob 59ec517f9 | lei tag -F eml +kw:flagged +L:next
+
+Set the "flagged" keyword and "next" label on the message with the
+blob OID of 59ec517f9.
+
+=back
+
+=head1 EXTERNALS
+
+In addition to the above store, lei can make read-only queries to
+"externals": inboxes and external indices.  An external can be
+registered by passing a URL or local path to L<lei-add-external(1)>.
+For existing local paths, the external needs to be indexed with
+L<public-inbox-index(1)> (in the case of a regular inbox) or
+L<public-inbox-extindex(1)> (in the case of an external index).
+
+=head1 SYNCHRONIZATION
+
+lei currently has primitive mail synchronization abilities;
+see L<lei-mail-sync-overview(7)> for more details.
+
+=head2 EXAMPLES
+
+=over
+
+=item $ lei add-external https://public-inbox.org/meta/
+
+Add a remote external for public-inbox's inbox.
+
+=item $ lei add-external --mirror https://public-inbox.org/meta/ path
+
+Clone L<https://public-inbox.org/meta/> to C<path>, index it with
+L<public-inbox-index(1)>, and add it as a local external.
+
+=back
+
+=head1 SEARCHING
+
+The L<lei-q(1)> command searches the local store and externals.  The
+search prefixes match those available via L<public-inbox-httpd(1)>.
+
+=head2 EXAMPLES
+
+=over
+
+=item $ lei q s:lei s:skeleton
+
+Search for messages whose subject includes "lei" and "skeleton".
+
+=item $ lei q -t s:lei s:skeleton
+
+Do the same, but also report unmatched messages that are in the same
+thread as a matched message.
+
+=item $ lei q -t -o /tmp/mdir --mua=mutt s:lei s:skeleton
+
+Write results to a Maildir at "mdir".  Mutt will be invoked
+to open mfolder (C<mutt -f %f>) while results are being fetched
+and written.
+
+=item $ lei q kw:flagged L:next
+
+Search for all flagged messages that also have a "next" label.
+
+=item $ lei p2q HEAD | lei q -tt -o /tmp/mdir
+
+Search for messages that have post-image git blob IDs that match those
+of the current repository's HEAD commit, writing them to the Maildir
+directory "mdir" and flagging the messages that were an exact match.
+
+=item $ git show -s HEAD | lei lcat
+
+Display a local message for the public-inbox link contained in a
+commit message.
+
+=item $ lei q -f text m:MESSAGE-ID | lei rediff -U5
+
+Feed a message containing a diff to L<lei-rediff(1)> to regenerate its
+diff with five context lines.  Unless C<--git-dir> is specified, this
+requires the current working directory to be within the associated
+code repository.
+
+=back
+
+=head1 PERFORMANCE NOTES
+
+L<Inline::C> is required on BSDs and can speed things up on Linux.
+
+lei runs as a background daemon to reduce startup costs and can
+provide real-time L<kqueue(2)>/L<inotify(7)> Maildir monitoring.
+L<IO::KQueue> (p5-IO-KQueue on FreeBSD) and L<Linux::Inotify2>
+(liblinux-inotify2-perl and perl-Linux-Inotify2 in .deb and .rpm-based
+distros, respectively) are recommended.
+
+L<Socket::MsgHdr> is optional (libsocket-msghdr-perl in Debian),
+and further improves startup performance.  Its effect is most felt
+when using shell completion.
+
+=head1 BASH COMPLETION
+
+Preliminary Bash completion for lei is provided in
+C<contrib/completion/>.  Contributions adding support for other
+shells, as well as improvements to the existing Bash completion, are
+welcome.
+
+=head1 UPGRADING
+
+Since lei runs as a daemon, L<lei-daemon-kill(1)> is required to kill
+the daemon so it can load new code.  It will be restarted with the
+next invocation of any lei command.
+
+=head1 CAVEATS
+
+IMAP and NNTP client performance is poor on high-latency connections.
+It will hopefully be fixed in 2022.
+
+=head1 CONTACT
+
+Feedback welcome via plain-text mail to L<mailto:meta@public-inbox.org>
+
+The mail archives are hosted at L<https://public-inbox.org/meta/> and
+L<http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/meta/>
+
+=head1 COPYRIGHT
+
+Copyright all contributors L<mailto:meta@public-inbox.org>
+
+License: AGPL-3.0+ L<https://www.gnu.org/licenses/agpl-3.0.txt>
+
+=head1 SEE ALSO
+
+L<lei-mail-sync-overview(7)>