Under the Pop3 server config, make sure "Offer only unread mail to connected clients" is unticked.

This is really the only Mercury setting that effects this process, it is up to the client which messages to request.

"Mark retrieved mail as read" may or may not have an effect, you will have to experiment.

I've spent the day installing Mercury and tryng it out.

I have got it to receive mail and put it into the default user's mailbox (using a domain mailbox)

I am then using my mail client to retrieve the mail via POP3 without deleting it from the server.

That is all working fine.

However, if I delete the downloaded mail from my mail client it is not being downloaded again.

Obviously Mercury knows it has already been downloaded and it is not offering it a second time.

This is not the  way I am used to working.  My ISP's server offers all mail on the server at every connection and it is my email client that decides what it has got and what is new.

Can I change the behaviour of Mercury to match my old way?

Or can I at least manually force Mercury to forget history and offer all existing mail again - I am thinking in terms of recovering mail if it is lost locally.

Many thanks.