MailCOPA will help you with your SPAM problems. The MailCOPA email client has inbuilt SPAM detection filters that require no tuning or setup. As every message is received it is scanned and scored. If the score exceeds the threshold then the message is delivered to your SPAM folder.
MailCOPA also features black and white SPAM lists. Anyone in any of your address books are automatically assumed to be on your white list, but you can easily add other addresses too. Users on your white list will not have their email checked for SPAM. While users on your blacklist will always be considered spammers. Add an entire domain to the blacklist and any email from that domain will be considered SPAM.
Adding messages to the SPAM black and white lists is simply a matter of dragging a message to or from the SPAM folder allowing you to build comprehensive lists almost subconsciously.
The MailCOPA email client also has a built in Bayesian filter, which learns what type of messages you consider to be SPAM and what you consider to be good messages.
You can also create your own filters which will increase of decrease the spam score based on elements of the message.
If that wasn't secure enough, the MailCOPA email software can also check online SPAM DNS Black Lists such as the Spamhaus DNSBL