The USPS has the following tips for ensuring your envelope makes it to its destination in the least amount of time:
Keep graphics and text away from the two barcodes on your envelope. No objects should be placed within 5/8" of the two barcodes, and nothing should be placed after the lower barcode.
One inch on either side should separate the Address object from additional text and graphics. The Address object should be a maximum of 2 3/4" from the bottom of the envelope. The Return Address should be no lower than