You can use any internet based mail on Outlook Express (OE). Non-internet based e-mail include corporate e-mail (the stuff you get at work) that use Exchange (or equivalent) e-mail servers. In these cases you use Outlook. POP is the Post Office Protocol (usually version three, thus POP3) which is the language that the e-mail client (OE) picks up mail from a POP server. They usually have obvious fully qualified domain names (FQDN) like pop.ntlworld.com or pop.freeserver.net that relate to your e-mail account. To send e-mails you use the simple mail transfer protocol (smtp). These are often restricted to whatever your internet service provider (ISP) is. If your ISP is ntlworld then the smtp server is smtp.ntlworld.com. You would not be able to use smtp.freeserver.net to send mail if your ISP was ntlworld. However, you will be able to pickup mail from freeserve even if your ISP was ntlworld. Sometimes the pop and smtp servers are the same (eg mail.btopenworld.com). Instead of using the FQDN (I hope you are keeping up) you can use an internet protocol (IP) address like 62.253.162.40 instead of smtp.ntlworld.com.