Economical security envelopes save you from having to wet the flap to seal. Just peel the strip and it seals. I was concerned whether these would go through our inkjet printer but they do just fine. So you can enter your addresses into the computer and print directly on the envelopes.
The self seal ends about 1/2 inch in from the side edges of the envelope flap. This makes them prone to tearing and being damaged by Post Office handling systems. I normally have to add scotch tape at the ends of the flap to avoid that. Self seal should be for the entire width of the envelope flap.