Do you know that personalized return address labels on your envelopes will look so much better if you designed it yourself? I don’t see why you shouldn’t inject a little color onto your mails, because it’s so easy to get them done via 123print.com. These labels will instantly let your receivers anticipate more joy before opening the actual letters or cards, and helps them build anticipation too 
I find these labels very pleasing to the eye and besides, after you have had them you can’t go back to plain old white labels every again! I’ve had some done for my sister’s baby shower and I was never happier with the end results!