In ye _really_ olden days people used to read email on a box connected to a large server somewhere, using a textbased piece of software like elm (for electronic mail) or pine (because geeks like puns).

A bit later, people needed to be able to download email from a server onto their own machines so they could read them there, and free up some more space in their online mailbox. To do this they used the Post Office Protocol (or POP) to connect, download all new emails and then disconnect again. The problem with this was that once you'd downloaded them onto your computer they couldn't easily be on any other computer. Which meant that you ended up either forwarding them to your other accounts (or yourself) to read later, or just doing without.

And then came IMAP. the Internet Message Access Protocol. This allowed you to leave the messages on the server, which would keep them _forever_ - and your email client would connect to it and just tell you what messages were sitting there. If you marked a message as read (or replied to) then that marking would happen _on the server_ and you would see exactly the same view no matter what computer you were on.

However, some geeks had been using the internet for a very long time, or had been told once that POP was how you downloaded email, and they never tried out IMAP, despite it being much more useful. Especially now that you can have gigabytes of email sitting online without worrying about space restraints.

But nowadays even GMail supports it. And it's dead handy. So give it a go.

(This post prompted by johanna_alice, who wass having problems reading email on two machines, and was doing all sorts of complex things to work around it, when IMAP would have solved the problems instantly.)