Experimental email transfers between separate computer systems began shortly after the creation of the ARPANET in 1969.[28] Ray Tomlinson is generally credited as having sent the first email across a network, initiating the use of the "@" sign to separate the names of the user and the user's machine in 1971, when he sent a message from one Digital Equipment Corporation DEC-10 computer to another DEC-10. The two machines were placed next to each other.[32][57] Tomlinson's work was quickly adopted across the ARPANET, which significantly increased the popularity of email.