Ryan Hughes wrote Furthermore with most POP servers, it causes an unnecessary high load on the server side, by copying the whole mailbox to a temporary file on every new POP connection. If you don't delete mail your mailbox can reach a considerable size.
mmm... scaling.
If POP get's implemented sometime into Worldpilot it will be used as a download protocol to retrieve mail to be stored in a "local" worldpilot storage, but would require removing it from the POP server. We're currently refraining from implementing it, since it does require some thought in regard to browser timeouts.
Our IMP-based solution on www.ekno.com and www.ekit.com implements POP as 'fetch from remote POP server into local IMAP store'. That works ok. It also means you can keep the logic of displaying messages cleaner. Anthony