Can 127.0.0.1 be a POP3 address?

Yesterday, I went to my customer's place to do the onsite job.

I found in one computer, winxp pro sp2, in outlook express, the POP server was set to 127.0.0.1 but it worked., I mean it received email properly.

Because it was the onsite service, I did not have enough time to delve this issue. I just guessed there problably was a "POP" agent program running on it. But hey, does it really need such a agent if my guess is correct? Becuase I checked ohter computers' POP server point to ISP's POP3 Server.

Can anyone explain it? Thanks in advance.

 

To add to Steve R. Jones' observation, it is almost a necessity for any active SPAM filter to redirect localhost to work. There is nothing unusual about this, and return is returned to your HOSTS file definition.