What's great about Popcorn is that it downloads mail headers only, you can then delete the mail off the mailserver and never retrieve the full mail. This can be good for those on dial-up with friends sending huge attachments or victims or massmail attacks. Also means this program is good for on the move.
This, of course, is exactly what nPOPuk will do.
The default is to download the first 100 lines, which is fine for reading the text of a message without downloading the HTML part or any larger attachment, but it can be changed to zero if you are using it for clearing out spam, etc.
I haven't seen the latest version of Popcorn, which may have additional features to the last freeware version I saw. For example, when I last looked it didn't offer mail filters or "Saveboxes".
POPuk has grown to be very much more than a "mail checker with reply facility" that is all Popcorn was. nPOPuk now functions as a full mail client. (I have given up using Outlook completely, and use it as my sole e-mail client - with "UK's Kalender" as my diary program -- and WAB as my address book, until I find something better!) It offers not only multiple accounts, but multiple "saveboxes" as well, folders into which mail can be sorted. Filters can be set to do this automatically on arrival. A backup option makes it easy for me to read old mail long after it was deleted from the server.
Other features which make it attractive for me include:
# Option to download full headers for debugging/tracking purposes
# Proper handling of forwarded mail with attachments
# Options to allow/prevent top-posting of replies/forwarded mail with fully customisable quotation headers for either replies and forwards.
# Optional stripping of tags from HTML mail with no text part so the text remains readable.
# Address Book which allows addresses to be grouped into multiple categories.
I'm sure there are other features that will be of interest to others - especially those with PDAs. I don't have one, so when travelling, my mail goes on a USB drive.