Mailwasher - Over 8 million people use MailWasher as their spam filter
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
SPAMfighter - SPAMfighter and Microsoft have built the strongest and most effective anti spam filter for Outlook, Windows Live Mail, Outlook Express & Thunderbird
tawk.to - tawk.to is a free live chat app that lets you monitor and chat with visitors on your website or from a free customizable page
Spam Reader - Spam Reader is a free anti-spam add-on for Microsoft Outlook.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.