Electronic mail, known more commonly as e-mail, uses communication facilities to transmit messages. A user can send a message to a single recipient or to many different recipients at one time. Different systems offer different options for sending, receiving, manipulating text, and addressing. For example, a message can be “registered,” so that the sender is notified when the recipient looks at the message (though there is no way to tell if the recipient has actually read the message). Email messages may be forwarded to other recipients. Usually messages are stored in a simulated “mailbox” in the network server or host computer; some systems announce incoming mail if the recipient is logged onto the system. An organization (such as a corporation, university, or professional organization) can provide electronic mail facilities; national and international networks can provide them as well.