Basic functionality works, if clunky. Barcodes are wrong.

Yes, this app can print envelopes. It works. The custom envelope size support is quite elegant. However, there are several big problems. On recent versions of Mac OS X, text entered into the address fields can appear cut off if the address is more than a couple lines long, which means you have to type it in blindly. The Intelligent Mail Barcode feature doesnt produce barcodes that pass the USPSs validation - they dont encode the delivery point correctly and every envelope is printed with the serial number 0, instead of a unique serial.
If you just want to print envelopes with addresses, and youre OK wading through a slightly clunky user interface, this app will work for you. If you want more advanced features, look elsewhere.

justaknife about EasyEnvelopes