ENVELOPE PROCESSING APPARATUS AND IMAGE FORMING SYSTEM

An envelope processing apparatus includes a flap opener, a first envelope detector, a second envelope detector, and circuitry. The flap opener opens a flap of an envelope during conveyance of the envelope in an envelope conveyance passage in which the envelope is conveyed to an enclosing position. The first envelope detector detects the envelope at a position upstream from the flap opener in a conveyance direction of the envelope. The second envelope detector detects the envelope at a position downstream from the flap opener in the conveyance direction. The circuitry causes the flap opener to execute an opening operation of the flap of the envelope conveyed to the enclosing position and causes the flap opener to execute the opening operation of the flap again when an opening-and-closing state of the flap determined based on detection results of the envelope by the first and second envelope detectors is abnormal.