“Official” Envelopes
Be careful with “official” envelopes. Faux express envelopes, government notices and other formats can be used to great effect. However, be clear about your intentions. If it’s just part of the theme of your message, and people are clear about who you are and what you want, that’s fine. If you’re trying to trick people or pose as something you’re not, that’s unethical. If you have to deceive people to get response, there’s something wrong with your product or service.