RFC 757 September 1979 Names and Addresses Page 3 2. While this should always result in a unique handle for that user, it has proved to be inadequate in practice. Users who change the location of their mailboxes, because of either a change in affiliation or a simple shift in host usage, also get their names changed. If their old host employs an MFDB the problem is not too bad. Mail is simply forwarded on to the new address, slightly delayed.
Any mail addressed to the old address becomes undeliverable.
The solution proposed here calls for a total break between the way a recipient is named or identified and the way in which his location is specified. This ID would stay with the user throughout his lifetime on the network, through changes in address and affiliation. RFC 757 September 1979 Names and Addresses Page 4 associated with an ID, that would indicate an ordered preference in delivery points. The delivery system would attempt delivery to the first addressee, and, if that failed, try the second, and 3 so on . Most IDs would probably have only one address.