What are open mail relays?

Some articles on mail:

Emailable - Operation Overview
... a typical sequence of events that takes place when Alice composes a message using her mail user agent (MUA) ... and uses the Submission Protocol (a profile of the Simple Mail Transfer Protocol (SMTP), see RFC 6409) to send the message to the local mail submission agent (MSA), in this case smtp.a.org, run by Alice's ... to determine the fully qualified domain name of the mail exchange server in the Domain Name System (DNS) ...

Famous quotes containing the words open and/or mail:

    Only in a house where one has learnt to be lonely does one have this solicitude for things. One’s relation to them, the daily seeing or touching, begins to become love, and to lay one open to pain.
    Elizabeth Bowen (1899–1973)

    We grew up founding our dreams on the infinite promise of American advertising. I still believe that one can learn to play the piano by mail and that mud will give you a perfect complexion.
    Zelda Fitzgerald (1900–1948)