Abstract: Apparatus for printing of mailing inserts prepackaged within envelopes and for printing of the envelopes also as desired simultaneously wherein specifically both sides of one or more inserts can be printed as desired by one pass through a computer controlled printer. Printing can be controlled for both sides of any inserts as well as the obverse or reverse surface of the front and back sheets which form the envelope. Inking means preferably in the form of carbon layers are carried at selected locations along the obverse and reverse surfaces of all inserts and each envelope sheet in such a manner as to allow impact printing on desired surfaces. The impact printer has the capability of printing both forward or conventional characters and reverse characters which are rotated about a vertically extending axis to facilitate printing on the reverse surfaces of insert sheets and envelope sheets.