It works pretty simply. Here's a screen shot of the interface:
All you do is add accounts by giving the POP server name then user name and password. You can select to view all mail messages for all accounts or just specific accounts. When you do, it looks at the POP server and shows the messages. Delete them, blacklist them by filling in check boxes next to each message....or do nothing. When you click the Process Mail button it performs the appropriate action. You can also preview the emails if you like but it doesn't handle HTML and will only show you the body of the message in text if it exists that way.
When you click the Mail Program button, Mailwasher will launch your email client...if you use one and provide the path to the program. Technically speaking, you can use the email provider's web interface and do the same thing but Mailwasher lets you do it all from one screen...without downloading any messages to your machine.
I think that about covers it. Any other questions, lemme know.
I've used Mailwasher for years -- this is the third computer to have it installed. It's simple -- the mail stays on the server and gets deleted from there. It never gets to your computer.
I have MS Outlook set up to receive when I click the "Send/Receive" button. You set that up in the "Options" section of Outlook. Open Mailwasher, look over your e-mail, blacklist the obvious spam, delete the stuff you just don't want to receive (Uncle Harry's 15th version of "The Priest, The Rabbi, and the Bartender" joke, etc.), hit "Process," and Mailwasher will open Outlook when it finishes getting rid of the trash.
Once Outlook opens, click "Send/Receive." The e-mail you want is then downloaded.
It's not necessary to set up Outlook like that. I've done that because I share this computer, and sometimes my loving family forget to run Mailwasher before opening Outlook. This way, they can't accidentally download a virus.