This is known as a partially qualified address. The full address should always be used. There are other addressing schemes in use, and very occasionally some users will need to be aware of these. These are documented in the Miscellaneous email page . Multimedia Messages One of the past limitations of email is that it was restricted to text.
Email containing types of data other than text is known as multimedia email.
Several solutions have been devised to allow transfer of non-textual information using email but some of these depend on the same software being employed at both the sending and receiving system, or conversion software available on the receiving system. Most of these ad hoc solutions were based on uuencoding. The standard way of dealing with multimedia email is called MIME - Multimedia Internet Mail Extensions. The non-textual information is supplied in a file and is known as an attachment. . MIME MIME is a standard developed as a set of extensions to SMTP - the standard email protocol in use on Internet.