Sealing them isn't bad. Just apply a heavy duty steamer to a pile of envelopes for 1/2 hour or so.
The tricky part is when you're done printing and have to unseal the envelopes so they can be used.
We always seal our envelopes before printing including the peel & seal type, we deliver them to the customer sealed, so it's their problem after that. We don't seem to get a lot of repeat envelope orders![]()