If you do not want your e-mail account to be full of garbage mail, you need to install an anti-spam, and spamhiliter may be a really good choice.
Thanks to a powerful filter system, Spamihilator works on your mail manager and on your server, so you can be aware of them.
You just have to insert your user and server and it will work together with your e-mail client and with the second line: Outlook, Mozilla, Eudora, Pegasus, Opera, Netscape, and more.
It can be highly configurable so if you are an advanced user but it can meet all your requirements, but if you are a stranger then install it and let it work, it will be really useful.
Of course, if it detects an e-mail spam and you do not think so, then you can mark it as a good e-mail.