前もってお礼を申しあげておきます。

in advance; beforehand; previously

thanks; gratitude; manners; etiquette; bow; reward; gift; ceremony; ritual

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to say; to tell; to state; to express; to offer; to extend (greetings, congratulations, etc.); to do