use proper 'Message-Id' field

app/controllers/webhooks_controller.rb

@@ -7,7 +7,7 @@ class WebhooksController < ActionController::Base
     return mailgun_failure if SiteSetting.mailgun_api_key.blank?
 
     # token is a random string of 50 characters
-    token = params.delete("token")
+    token = params["token"]
     return mailgun_failure if token.blank? || token.size != 50
 
     # prevent replay attack
@@ -16,14 +16,14 @@ class WebhooksController < ActionController::Base
     $redis.expire(key, 10.minutes)
 
     # ensure timestamp isn't too far from current time
-    timestamp = params.delete("timestamp")
+    timestamp = params["timestamp"]
     return mailgun_failure if (Time.at(timestamp.to_i) - Time.now).abs > 24.hours.to_i
 
     # check the signature
     return mailgun_failure unless mailgun_verify(timestamp, token, params["signature"])
 
-    event = params.delete("event")
-    message_id = params.delete("message-id")
+    event = params["event"]
+    message_id = params["Message-Id"].tr("<>", "")
 
     # only handle soft bounces, because hard bounces are also handled
     # by the "dropped" event and we don't want to increase bounce score twice

spec/controllers/webhooks_controller_spec.rb

@@ -4,13 +4,13 @@ describe WebhooksController do
   before { $redis.flushall }
 
   let(:email) { "em@il.com" }
+  let(:message_id) { "12345@il.com" }
 
   context "mailgun" do
 
     it "works" do
       SiteSetting.mailgun_api_key = "key-8221462f0c915af3f6f2e2df7aa5a493"
 
-      message_id = "12345@il.com"
       user = Fabricate(:user, email: email)
       email_log = Fabricate(:email_log, user: user, message_id: message_id)
 
@@ -19,7 +19,7 @@ describe WebhooksController do
       post :mailgun, "token" => "705a8ccd2ce932be8e98c221fe701c1b4a0afcb8bbd57726de",
                      "timestamp" => Time.now.to_i,
                      "event" => "dropped",
-                     "message-id" => message_id
+                     "Message-Id" => "<12345@il.com>"
 
       expect(response).to be_success
 
@@ -34,7 +34,7 @@ describe WebhooksController do
 
     it "works" do
       user = Fabricate(:user, email: email)
-      email_log = Fabricate(:email_log, user: user, message_id: "12345@il.com")
+      email_log = Fabricate(:email_log, user: user, message_id: message_id)
 
       post :sendgrid, "_json" => [
         {
@@ -57,7 +57,6 @@ describe WebhooksController do
   context "mailjet" do
 
     it "works" do
-      message_id = "12345@il.com"
       user = Fabricate(:user, email: email)
       email_log = Fabricate(:email_log, user: user, message_id: message_id)