lick envelopes?

[David Jonsson]

I used to use regular #10 envelope (standard business size) 4 1/8" by 9 1/2" to stuff my yellow letters. I would only tuck sleeve in, (not lick it) so its easy to open. I just switched to A2 invitation style envelopes 4.375" x 5.75" from Office Depot. Again I did not lick these to seal shut. Im concerned they might get jammed up in post office sorting machines, due to edges catching and ripping or whatever because I didnt seal them shut, but just tucked closed again. Any advice? should i lick them or just tuck? thanks