I have often been asked the question if printing guest's addresses on the envelope is proper. Traditionally, no it's not ... however I am definitely not opposed to it! I think it is a nice alternative if you don't have the budget to hire a calligrapher.
Here you can see how I used script fonts to appear as if they were done by a calligrapher. They turn out fabulous! I love placing the return address on the back flap leaving the front a clean canvas to house a vintage set of stamps and your guest's address.
Couture Invitations offers machined calligraphy to complete your invitation suite! Definitely a great way to pull everything together.