A couple of issues ago I wrote an article explaining why you shouldn't use a laser printer to type envelopes. The reasons were compelling * a laser image is essentially a pile of toner dust melted into a raised pile on the envelope. This toner bubble tends to crack and flake off as it runs through the USPS sorting and bagging gizmos. The envelopes look great coming out of the laser but look like they were routed through Lebanon by the time they reach your intended recipient.
I was right. And now I've been proven wrong ... sort of. Standard laser printers have the problem I mentioned above. But the new HP LaserJet 4si series printer almost eliminates this problem. I say almost because the flaking and cracking problem still exists, but to a much lesser degree.
The new 4si printer uses "microfine" toner (the toner dust is about half the normal size) and 600 dpi (dots per inch) letter formation. What this techno mumbo-jumbo means is the toner is smaller so it creates less of a raised pile of toner after the image has been melted or "fused" to the page. And if the raised bubble is smaller, there's less chance of scraping the image off the envelope. Hence the delivered envelope looks much nicer than with other models of laser printers.
In addition, the 600 dpi and smaller toner particles make for a sharper image. Combine this with a handwriting or script typestyle (my favorite is one called Pencil Point Italic, which looks exactly like an architect's printing) and your envelopes will really stand out. Major stumbling block: The printer sells for about $3100 plus $450 for an envelope feeder. Better option: Use a service bureau that has this capability. Service center cost: about 5 cents to 7 cents per envelope.
Note: I still recommend using a daisy wheel or inkjet printer for large printing runs. Your overall cost will be less and the envelopes will still hold up better through the mail. But the new HP 4si printer offers a nice compromise.