A number of tools have come out that can help you manage your e-mail inbox more efficiently and effectively:
Boomerang: Compatible with Firefox 3.6+, Chrome 5.0+ and Safari 5.1+, Gmail and Outlook on PC
Your email gets lost in the shuffle, the add-on lets you set the time and date of delivery (Schedule), and this helps you to plan ahead of time. The tool also allows you to control when you send and receive e-mails. Boomerang also allows you to set follow-up reminders for outgoing e-mails.
Rapportive: Available for Gmail or Mailplane on any type of computer or mobile device
Rapportive is a tool that is owned by LinkedIn. Most people want to always see that they monitor both their mail and social media platform at the same time, with this tool it will be able to do that for you. The tool only supports Facebook, Twitter and LinkedIn.
FollowUpThen: Compatible with all email accounts
According to Design Sponge, FollowUpThen is a simple system for e-mail follow-up where you forward e-mails to @FollowUpThen and then use @followupthen in the BCC or TO lines to schedule a reminder for yourself only, or CC to schedule a reminder for you and the recipient.
Inky: Available for Gmail, Outlook, Yahoo, and other email programs on PC or Mac
Inky helps you to analyze incoming messages and then filters them so that you can focus on the most important ones first. Organizes all your messages in a way that the important ones will rise to the top of your inbox, while the promotional and less urgent communications sink.
Mailstrom: Compatible is most of the email accounts
Mailstrom helps you to understand your e-mail patterns and to set up filters accordingly. Plus you can view your e-mails by sender, subject, lists, time, social, shopping, and size.
Zoomin: Available for Outlook on PC or iPhone
When you need to respond to your contacts quickly, Zoomin tool will be the best for you in this case. The plug-in also climaxes communications from important contacts. Additionally, the Outlook tool helps you to see a summary of your mails minus you opening the email.
Enjoy using these great e-mail tools.
Thanks for mentioning Inky! Inky also works on Android and allows users to tag messages and senders, and even lets you save searches.