Reading POP3 Email... or widgetize?

[eluser]codelearn[/eluser]
Hey guys,

I have a general question to the experienced PHP'ers in this forum. My company (a dot com) wants to enable its users to be able to read their POP email from our page instead of through their regular email source.

My question is about the resource intensity of the various PHP scripts which I found on the web that enable me to do this exact thing. We have a fairly large amount of users, and I know that sites like Mail2Web have a large server farm to handle this sort of thing.

Anyone here in the know about a CI Library written for this purpose, or the resources necessary to run an operation of that scale?

Thanks.

EDIT: Forgot to mention: our second option is to partner with a company like Mail2Web so they can provide us with the necessary widget.