The most envelopes torn in half in 30 seconds is 46 and was achieved by Stephen Kish (UK), in Hove, East Sussex, UK, on 17 September 2013.

This record was broken on the Guinness World Record Challengers site (Challengers’ tag: Oddish196): http://challengers.guinnessworldrecords.com/challenges/244-most-envelopes-torn-in-half-in-30-seconds/attempts/4334