The Ultimate Email Filtering

I’ve posted plenty about email before, so it might not be surprising that along with all of my other tooling, I have some email filtering tools as well. I recently rewrote most of my filtering tools after being inspired by my friend and coworker Meredith’s email filtering. It’s pretty cool!

🔗 The Old

The old way that I filtered my mail involved a script that cron would run once a minute, using the notmuch email index and basically moving the files in a given search somewhere. Here’s an small bit of it:

export NOTMUCH_CONFIG="$HOME/.zr-notmuch-config"

_safe_mv() {
   local dest="$1"
   if [ -n "$1" ]; then
      mv "[email protected]" "$dest"

archive() rm -f "[email protected]"
trash() _safe_mv $MAILDIR/gmail.Trash/new "[email protected]"
search() notmuch search --output=files "[email protected]" folder:INBOX
thread() {
   notmuch search --output=threads "[email protected]" folder:INBOX | \
      xargs -I{} -n1 notmuch search --output=files folder:INBOX {}

days_ago() perl -MDateTime -E"say DateTime->now->subtract(days => $1)->ymd(q(-))"
days_old() echo "date:..$(days_ago $1)"

archive $(search '"SECURITY information for some-weird-server"' '"unable to resolve host"')

# delete production errors email that is older than todays
archive $(search 'fluentd.error summary' "$(days_old 1)")
archive $(search 'Production errors from yesterday' "$(days_old 1)")
archive $(search 'heavy queries' "$(days_old 1)")

# squelch noise till after next release
if [ "$(date +%Y%m%d)" -lt "20160628" ]; then
   archive $(search '"Use of uninitialized value $sub_status in pattern match (m//)"' from:root)

I am and was pretty proud of this set of functionality. If I wanted to quickly filter a given sender, I could just add a line to bin/clean-email. I could archive emails that were effectively replaced by a new one the next day. And finally I could add ad-hoc date triggered filters that would go away after a given day.

There are a few problems here:

  • If my laptop is off, email doesn’t get filtered. Annoying for phone email.
  • If I want to move the code to a server, I need a full copy of my email on the server.
  • There is an annoying bit of lag where the email shows up in my inbox and won’t go away for about 60s.

🔗 The New

Meredith mentioned at some point that she had a script that filtered email in a similar way to mine, but it ran on Google’s servers! She shared it with me and I looked into making my own version. Before proceeding though I went through the annoying but reasonable process of converting the simple non-date based searched into standard server-side filters. I have resisted that in the past just because it’s such a hassle compared to editing a text file, but it’s legitimately the best option so I will just get used to it (till I make a tool to sync from a text file of course.)

So the gist of it is that there’s this thing called Google App Script, which is JavaScript with some API access running on their servers. The docs are here. I ended up writing the following, and having it run once a minute:

function archiveInbox() {
  var count;
  var searches = [
    'older_than:1d fluentd.error summary',
    'older_than:1d "Production errors from yesterday"',
    'older_than:1d "heavy queries"',
    'older_than:8d from:cron',
    'older_than:8d from:[email protected]',
  for (var i = 0; i < searches.length; i++) {
    archive('in:inbox ' + searches[i]);

function archive(search) {
  var count;
  do {
    count = archiveInboxIncremental(search);
  while (count !== 0);

function archiveInboxIncremental(search) {
  var threads =, 0, 50);

  Logger.log('Archived %s threads for %s', threads.length, search);
  return threads.length;

This is defintely less convenient than editing a local script, but it runs all the time and not on my own infrastructure. Stay tuned for the next post where I show how I wrote a script for fixing emails that don’t thread right.

Posted Sat, Oct 29, 2016

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