Can you mail red envelopes and what size should they be?

Mailing a red envelope is acceptable when distance makes attendance impossible, though handing it over personally is more traditional. If you send it by post, use a sturdy envelope to protect the cash and choose a reliable service. Standard invitation sizes are a good fit, as they hold banknotes flat without creasing them. Avoid envelopes that are too small, since folded notes can look careless. Make sure the envelope is sealed securely so nothing is lost in the post. It is also kind to let the couple know you are sending it, so they can expect it. Some families keep a record of gifts sent by post, so include your name on an accompanying card. If the wedding is soon, consider asking a trusted guest to deliver it instead. The couple will appreciate the thought regardless of how you deliver it.