support alternative email addresses for mailing lists

Author: dutow

app/controllers/admin/mailing_lists_controller.rb

@@ -54,6 +54,10 @@ def set_mailing_list
   end
 
   def mailing_list_params
-    params.require(:mailing_list).permit(:identifier, :display_name, :email, :description)
+    permitted = params.require(:mailing_list).permit(:identifier, :display_name, :email, :description, :alternate_emails)
+    if permitted[:alternate_emails].is_a?(String)
+      permitted[:alternate_emails] = permitted[:alternate_emails].split(/[\r\n,]+/).map(&:strip).reject(&:blank?)
+    end
+    permitted
   end
 end

app/models/mailing_list.rb

@@ -6,4 +6,16 @@ class MailingList < ApplicationRecord
 
   validates :identifier, presence: true, uniqueness: true
   validates :display_name, presence: true
+
+  def all_emails
+    [email, *alternate_emails].compact.reject(&:blank?).map(&:downcase)
+  end
+
+  def self.email_lookup_index
+    index = {}
+    where.not(email: nil).find_each do |ml|
+      ml.all_emails.each { |e| index[e] = ml }
+    end
+    index
+  end
 end

app/services/imap_idle_runner.rb

@@ -181,7 +181,7 @@ def resolve_mailing_lists_from_mail(mail)
     all_addresses.concat(Array(mail.to)) if mail.to
     all_addresses.concat(Array(mail.cc)) if mail.cc
 
-    known_lists = MailingList.where.not(email: nil).index_by { |ml| ml.email.downcase }
+    known_lists = MailingList.email_lookup_index
     all_addresses.filter_map { |addr| known_lists[addr.to_s.downcase] }.uniq
   end
 

app/views/admin/mailing_lists/_form.html.slim

@@ -17,6 +17,10 @@
     = f.label :email
     = f.text_field :email, placeholder: "e.g. pgsql-hackers@lists.postgresql.org", class: "form-input"
 
+  .form-group
+    = f.label :alternate_emails, "Alternate emails (one per line)"
+    = f.text_area :alternate_emails, value: mailing_list.alternate_emails.join("\n"), placeholder: "e.g. pgsql-hackers@postgresql.org", rows: 3, class: "form-input"
+
   .form-group
     = f.label :description
     = f.text_area :description, placeholder: "Optional description", rows: 3, class: "form-input"

db/migrate/20260326074352_add_alternate_emails_to_mailing_lists.rb

@@ -0,0 +1,5 @@
+class AddAlternateEmailsToMailingLists < ActiveRecord::Migration[8.0]
+  def change
+    add_column :mailing_lists, :alternate_emails, :string, array: true, default: []
+  end
+end

db/schema.rb

@@ -9,6 +9,16 @@
     it { is_expected.to validate_uniqueness_of(:identifier) }
   end
 
+  describe ".email_lookup_index" do
+    it "indexes by primary and alternate emails" do
+      ml = create(:mailing_list, email: "pgsql-hackers@lists.postgresql.org",
+                                 alternate_emails: ["pgsql-hackers@postgresql.org"])
+      index = described_class.email_lookup_index
+      expect(index["pgsql-hackers@lists.postgresql.org"]).to eq(ml)
+      expect(index["pgsql-hackers@postgresql.org"]).to eq(ml)
+    end
+  end
+
   describe "associations" do
     it { is_expected.to have_many(:message_mailing_lists) }
     it { is_expected.to have_many(:messages).through(:message_mailing_lists) }

spec/models/mailing_list_spec.rb

@@ -82,6 +82,37 @@
       expect(msg.mailing_lists).to include(hackers_list)
     end
 
+    it "resolves list from alternate email in CC" do
+      hackers_list.update!(alternate_emails: ["pgsql-hackers@postgresql.org"])
+      state = ImapSyncState.for_label("INBOX")
+      allow(imap_client).to receive(:connect!).and_return(true)
+      allow(imap_client).to receive(:disconnect!).and_return(true)
+      expect(imap_client).to receive(:uids_after).with(0).and_return([203])
+      raw = <<~MAIL
+        From: Test <test@example.com>
+        To: peter@eisentraut.org
+        CC: pgsql-hackers@postgresql.org
+        Subject: Re: SQL Property Graph Queries
+        Date: Fri, 1 Jan 2021 12:00:00 +0000
+        Message-ID: <uid-203@example.com>
+        MIME-Version: 1.0
+        Content-Type: text/plain; charset=UTF-8
+
+        Body
+      MAIL
+      expect(imap_client).to receive(:uid_fetch_rfc822).with(203).and_return(raw)
+      expect(imap_client).to receive(:mark_seen).with(203)
+      expect(imap_client).to receive(:idle_once).and_return(:timeout)
+      allow(imap_client).to receive(:uids_after).with(203).and_return([])
+
+      runner = described_class.new(client: imap_client, label: "INBOX")
+      runner.run(max_cycles: 1, idle_timeout: 1)
+
+      msg = Message.find_by(message_id: "uid-203@example.com")
+      expect(msg).to be_present
+      expect(msg.mailing_lists).to include(hackers_list)
+    end
+
     it "skips message when no list can be resolved" do
       state = ImapSyncState.for_label("INBOX")
       allow(imap_client).to receive(:connect!).and_return(true)