What are some alternatives?
When comparing MailScanner and SpamSieve, you can also consider the following products
Scrollout F1 - Scrollout is a free and easy to use anti-spam email gateway designed for Linux & Windows administrators without advanced email security experience.
Mailwasher - Over 8 million people use MailWasher as their spam filter
SpamAssassin - Use this program to "Unspam" your mailbox(es).
Spamihilator - The free Anti-Spam-Filter Spamihilator removes more than 98% of spam mails before they even get into your inbox.
Spamfence.net - Professional e-mail security free for private use: With Spamfence.
Altospam - Antispam and antivirus software on Cloud