Spamihilator - The free Anti-Spam-Filter Spamihilator removes more than 98% of spam mails before they even get into your inbox.
Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues
Mailwasher - Over 8 million people use MailWasher as their spam filter
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
SpamAssassin - Use this program to "Unspam" your mailbox(es).
K-9 Mail - K-9 is an opensource email client making it easy to chew through large volumes of email.