How do I send Internet mail?

One consequence of the new unacceptability of open relays was an inconvenience for some end users and certain internet service providers. To allow customers to use their e-mail addresses at Internet locations other than the company's systems (such as at school or work), many mail sites explicitly allowed open relaying so that customers could read and send e-mail via the ISP from any location. Once open relay became unacceptable due to abuse (and unusable due to blocking of open relays) ISPs and other sites had to adopt new protocols to allow remote users to send mail. These include SMTP-AUTH, POP-before-SMTP, and the use of virtual private networks (VPNs).