IMAP leaves everything on the server. Nothing is removed/deleted unless you do it yourself. If you don't want email in your inbox, just move it to a server folder, which also stays on the server.
POP on the other hand has no shared/synced folders, just your email. You only get two options. Download and delete, or download and leave. If you only access you mail on one device or computer; it works fine. If you want your email to behave the same on all devices and computers you need to use an IMAP or Exchange server; and keep all folders on the server (not locally on the iPad or Computer).
There are reasons to use POP, but everything stays on the server isn't a good one. It has several problems.
You're never sure what email is available on what device or computer.
If something happens to your POP account it can lose track of what emails were already downloaded to what device. When you hear someone complain that their Inbox is suddenly filled with old emails, POP is the usual cause. That's the download and leave option.
One device, either your computer or iPad should be set to Download and delete, to keep the above from happening, or from exceeding the storage limit many POP servers have. When doing this you need to always watch what device you check your email with last. If you check with the download and delete on the computer, the iPad will never see those emails it has not already downloaded.
If I sound strong on IMAP, I am. It takes just a bit more management, making sure you keep everything on the server instead of in local folders; but the payoff is that all your folders are exactly the same on all devices and in webmail. You never lose anything unless you deliberately delete it both from the inbox and from trash.
Anyway, after all that, it's always your choice. If you are happy with your current workflow and email behavior then it's all good.
But you were ♫ dun Dun dunnnn ♫ 'warned' .
