It’s just a little thing, but I like to see counts of messages in certain categories. As notmuch provides a count command, it is simple to write a script that will provide you with the counts you want. Here’s one I prepared earlier:

#!/bin/sh

# I'm interested in the thread count rather than individual messages
NMC="/usr/bin/notmuch count --output=threads"

# I break it down by total, how many are flagged and how many are unread
# This function produces a single line
function tag_report(){
  TAG=$1
  TOTAL_COUNT=$($NMC tag:$TAG)
  FLAGGED_COUNT=$($NMC tag:$TAG AND tag:flagged)
  UNREAD_COUNT=$($NMC tag:$TAG AND tag:unread)

  echo "$TAG: total $TOTAL_COUNT flagged $FLAGGED_COUNT unread $UNREAD_COUNT"
}

# then these are the tags I'm interested in, so print the reports
# one line per tag
function full_report(){
  tag_report inbox
  tag_report action
  tag_report waiting
  tag_report readlater
}

# finally, pipe through column to make the results line up nicely
full_report | column -t

I’ve chosen to do this by having a small tmux window above my mail client, using watch to refresh. The command I use is:

watch -t -n 300 bin/mailreport

The -t means don’t bother showing the time (saving a line of output) and the -n 300 means only run the report once every 5 minutes. The output (currently) looks like:

inbox:      total  28  flagged  4  unread  0
action:     total  55  flagged  4  unread  11
waiting:    total  13  flagged  2  unread  1
readlater:  total  60  flagged  2  unread  3