Q:

Mailboxer/Rails: Undefined method for 'sender='

I've been slaving at this problem for a day an a half now. I'm using the Mailboxer gem to to create a very cut-and-dried messaging system; one that's identical to the sample - https://github.com/RKushnir/mailboxer-app - just to start off with this gem. 
I literally have both repositories sitting next to each other on my computer. The mailboxer-specific models, migrations, initializers, everything I can find. This includes the User model, with the name action. I've even tried messing around with the Notification model with the attr_accessible.
The databases are identical.
When I try in the console/seeds to create a Message after a conversation is saved in the sample app, it's quite easy. Once the conversation is saved I run:
n = Message.new
n.sender = User.find(1)
n.subject = 'Hi'
n.body = 'Hello there.'
n.conversation_id = Conversation.find(1).id
n.save

And boom. It works beautifully. My app, on the other hand, will function identically; until it gets to the sender field.
When I try to set the sender:
n.sender = User.find(1)
I receive this error: NoMethodError: undefined method 'sender=' for #<Message:0x00000101708eb8>
Why??
This is driving me crazy. I would really be appreciative if someone could lend some assistance. Thank you in advance.
Message/Notification schema :
  create_table "notifications", force: true do |t|
    t.string   "type"
    t.text     "body"
    t.string   "subject",              default: ""
    t.integer  "sender_id",                            null: false
    t.integer  "conversation_id"
    t.boolean  "draft",                default: false
    t.datetime "updated_at",                           null: false
    t.datetime "created_at",                           null: false
    t.integer  "notified_object_id"
    t.string   "notified_object_type"
    t.string   "notification_code"
    t.string   "attachment"
    t.boolean  "global",               default: false
    t.datetime "expires"
  end

  add_index "notifications", ["conversation_id"], name: "index_notifications_on_conversation_id", using: :btree

This is what the gem generates, and it is identical to the sample app as well.

A:

Take a look at Mailboxer gem sent_message method here you might find it helpful.
You can also use the mailboxer built in send_message method to send message
sender = User.find(1)
receiver = User.find(2) 
sender.send_message(receiver,"Subject", "Body")

