"In the meantime with the highest respect, I am yours to command,"
"I have the honor to be, Sir, Your humble Servant,"
"With great expression of esteem, I am Sincerely yours,"
"Believe me, my dear Sir, Ever faithfully yours,"
are condemned as savoring too much of affectation.
It is better to finish formal letters without any such qualifying remarks. If you are writing to Mr. Ryan to tell him that you have a house for sale, after describing the house and stating the terms simply sign yourself
Your obedient Servant
Yours very truly,
Yours with respect,
James Wilson.
Don't say you have the honor to be anything or ask him to believe anything, all you want to tell him is that you have a house for sale and that you are sincere, or hold him in respect as a prospective customer.
Don't abbreviate the signature as: Y'rs Resp'fly and always make your sex obvious. Write plainly
Yours truly,
John Field
and not J. Field, so that the person to whom you send it may not take you for Jane Field.
It is always best to write the first name in full. Married women should prefix Mrs. to their names, as
Very sincerely yours,
Mrs. Theodore Watson.