Post cards are a versatile form of print advertising. Dynamic Digital Advertising, a professional custom graphic and website design company, creates post cards for any size or need. Sending post cards to announce address or company name changes is imperative to keeping customers and vendors informed. DDA, a leader in digital advertising in Philadelphia, Pennsylvania, New Jersey and Delaware, can make your post cards original and eye-catching. Post cards can be any shape and size as long as they meet postal requirements.