Hereto, Herewith, Thereto, Therewith

Avoid as far as possible full-dress compounds of this kind unless; like theretherefore, they have become part of every-day language. Most of them put a flavour of legalism into any document in which they are used. Use a preposition and pronoun instead.

With reference to the second paragraph thereof. (With reference to its second paragraph.)

I have received your letter and thank you for the information contained therein. (I thank you for the information contained in your letter.)

I am to ask you to explain the circumstances in which the gift was made and to forward any correspondence relative thereto. (. . . any correspondence about it.)

Do not say "I enclose herewith ". Herewith adds nothing to the sense. All it does is to put a touch of starch into the letter.