Email Meter - See how many emails your team deals with to understand their workload. Know how long they take to reply and where they can improve.
PixelBlock - Block email open tracking inside of Gmail
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Ugly Email for FireFox - Get back your email privacy, block email tracking
Mailpanion - Track your email clicks & prevent others from tracking you.
Email Privacy Protector - Check the presence of email ids on your webpages using Email Privacy Checker tool and protect yourself from email spammers.