The sender should also include their return address. In the United Kingdom, the Royal Mail will hold mail posted from within the UK for two weeks, whereas mail posted from abroad is normally held for one month. If the recipient is at sea however, it will be held for two months. Where mail is not collected within that time, it will be returned to the sender, or if there is no sender indicated, will be treated as undeliverable. If the sender would like uncollected mail returned sooner, they can indicate this on the envelope. Timescales vary from country to country according to local practice.