Pop/smtp

Hi,
I would like to know what exactly is ‘use pop before smtp’?
pop is used for downloading mails & smtp for sending mails. So how can you use pop before smtp?
Can someone explain?
Thanks,sal

My understanding is that POP before SMTP requires that users authenticate using the POP service in order to send mail. This however allows mail to be sent regardless of the IP address of the user. Without authenticating they can not utilize SMTP on the server. Here is the Wikipedia link. en.wikipedia.org/wiki/POP_before_SMTP. Hope this helps.