gmailctl

gmailctl

This utility helps you generate and maintain Gmail filters in a declarative way. It has a Yaml configuration file that aims to be more simple to write and maintain than using the Gmail web interface, to categorize, label, archive and manage automatically your inbox.

Motivation

If you have Gmail and have (like me) have to maintain a lot of filters to apply labels, get rid of spam or categorize your emails, then you probably have (like me) a mess of filters that you don't even remember what they are intended to do and why.

Gmail has both an import export functionality for filters (in XML format) and powerful APIs that we can access to update our settings. Editing these XML files is pretty painful because the format is not human friendly. The Gmail query language is quite powerful but not easy to remember.

This project exists to combine:

1. maintainability
2. powerful but declarative language
3. quick updates to your settings

Usage

go install github.com/mbrt/gmailctl/cmd/gmailctl
gmailctl init
# edit the config file
gmailctl apply -f config.yaml

where config.yaml is the configuration file containing the filtering rules (see Configuration). The utility will guide you through setting up the Gmail APIs and update your settings without leaving your command line.

NOTE: It's recommended to backup your current configuration before to applying a generated one. Your current filters will be wiped and replaced with the ones specified in the config file. Since bugs can happen in both code and configuration, always backup to avoid surprises.

Configuration

NOTE: The configuration format is still in alpha and might change in the future.

The configuration contains two important sections:

• consts that contains global constants that can be referenced later on by rules.
• rules that specify a set of filters that when match cause a set of actions to happen.

Rule evaluation

With the help of this example, let's explain how rules evaluation works:

- filters:
    filterA:
      - valueA
      - valueB
    filterB:
      - valueC
  # omitted actions

- filters:
    filterC:
      - valueD
      - valueE
  # omitted actions

1. If the filter of a rule matches, then it's applied. This means that every rule is in OR with all the others. In the example, given an email, if the first filter matches, then its actions are applied; if the second also matches, then its actions are also applied.
2. Within a rule, all the filters have to match, in order for the rule to match. This means that the filters inside a rule are in AND together. In the previous example, if only filterA matches, then the first rule is not applied. If both filterA and filterB match, then the rule also matches.

Filters

The following simple filters are available:

• from
• to
• subject
• has

You can apply the special not operator to negate a match in this way:

  - filters:
      not:
        to:
          - foo@bar.com
        subject:
          - Baz zorg

The rule will match if the email both is not directed to foo@bar.com and does not contain Baz zorg in the subject.

Constants

A filter can refer to global constants specified in the first section by using the consts section inside the filter. All values inside the rule will be replaced by the constants. Inside consts you can put again the same set of filters of the positive case:

• from
• to
• subject
• has

Example:

version: v1alpha1
consts:
  friends:
    values:
      - pippo@gmail.com
      - pippo@hotmail.com
rules:
  - filters:
      consts:
        not:
          from:
            - friends
    actions:
      archive: true

is equivalent to:

version: v1alpha1
rules:
  - filters:
      consts:
        not:
          from:
            - pippo@gmail.com
            - pippo@hotmail.com
    actions:
      archive: true

Example

This is a more "real world" example, taken from my configuration with scrambled values :)

version: v1alpha1
author:
  name: Pippo Pluto
  email: pippo@gmail.com

consts:
  me:
    values:
      - pippo@gmail.com
      - pippo@hotmail.com
  spam:
    values:
      - spammer@spam.com

rules:
# important emails
  - filters:
      from:
        - myalarm@myalarm.com
    actions:
      markImportant: true
      labels:
        - alarm
# delete spammers
  - filters:
  # here we need two rules because we want to apply them if the email matches
  # one OR the other condition (blacklisted subject or blacklisted sender)
      subject:
        - foo bar baz
        - I want to spam you
    actions:
      delete: true
  - filters:
      consts:
        from:
          - spam
    actions:
      delete: true
  - filters:
      has:
        - buy this
        - buy that
    actions:
      delete: true
# mail list
  - filters:
  # archive unless directed to me
      from:
        - interesting@maillist.com
      consts:
        not:
          to:
            - me
    actions:
      archive: true
      markRead: true

  - filters:
  # always apply the label (even if directed to me)
      from:
        - interesting@maillist.com
    actions:
      labels:
        - mail-list

Comparison with exising projects

gmail-britta has similar motivations and is quite popular. The difference between that project and this one are:

• gmail-britta uses a custom DSL (versus YAML in gmailctl)
• gmail-britta is imperative because it allows you to write arbitrary Ruby code in your filters (versus pure declarative for gmailctl)
• gmail-britta allows to write complex chains of filters, but fails to provide easy ways to write reasonably easy filters 1.
• gmail-britta exports only to the Gmail XML format. You have to import the filters yourself by using the Gmail web interface, manually delete the filters you updated and import only the new ones. This process becomes tedious very quickly and you will resort to quickly avoid using the tool when in a hurry. gmailctl provides you this possibility, but also allows you to review your changes and update the filters by using the Gmail APIs, without you having to do anything manually.
• gmailctl tries to workaround certain limitations in Gmail (like applying multiple labels with the same filter) gmail-britta tries to workaround others (chain filtering).
• chain filtering is not supported in gmailctl by design. The declarative nature of the configuration makes it that every rule that matches is applied, just like Gmail does.

In short gmailctl takes the declarative approach to Gmail filters configuration, hoping it stays simpler to read and maintain, sacrificing complex scenarios handled instead by gmail-britta (like chaining), and provides the automatic update that will save you time while you are iterating through new versions of your filters.

Footnotes

Footnote 1

Try to write the equivalent of this filter with gmail-britta:

version: v1alpha1
consts:
  spammers:
    values:
      - pippo@gmail.com
      - pippo@hotmail.com
  spamSubjects:
    values:
      - buy this
      - buy my awesome product
rules:
  - filters:
      consts:
        from:
          - spammers
    actions:
      delete: true
  - filters:
      consts:
        subject:
          - spamSubjects
    actions:
      delete: true

It becomes something like this:

#!/usr/bin/env ruby

# NOTE: This file requires the latest master (30/07/2018) of gmail-britta.
# The Ruby repos are not up to date

require 'rubygems'
require 'gmail-britta'

SPAM_EMAILS = %w{pippo@gmail.com pippo@hotmail.com}
SPAM_SUBJECTS = ['"buy this"', '"buy my awesome product"']

puts(GmailBritta.filterset(:me => MY_EMAILS) do
       # Spam
       filter {
         has [{:or => "from:(#{SPAM_EMAILS.join("|")})"}]
         delete_it
       }
       filter {
         has [{:or => "subject:(#{SPAM_SUBJECTS.join("|")})"}]
         delete_it
       }
     end.generate)

Not the most readable configuration I would say. Note: You have also to make sure to quote correctly terms when they contain spaces.

So what about this one?

version: v1alpha1
consts:
  friends:
    values:
      - pippo@gmail.com
      - pippo@hotmail.com
rules:
  - filters:
      from:
        - interesting@maillist.com
      consts:
        not:
          from:
            - friends
    actions:
      archive: true
      markRead: true