Best all-rounder; best for non-Outlook users.
Created by Mozilla, the same people behind the Firefox web browser, Thunderbird is minimalistic in design, offering simple options such as "Get Mail" and "Write". Setting up my email account was quick and easy, needing only my email address and password – no server settings here – with options to import my Calendar and Contacts alongside my mail.
Thunderbird filters out junk emails effectively, as would be expected from a renowned web brand. In fact, having Mozilla as the developer of Thunderbird is one of its greatest strengths; regular updates and bug fixes are forthcoming and support is good.
The clear and well designed interface sets Thunderbird apart, with over 1,000 add-ons – integration with social networks, design tweaks, and so on – coming as a bonus.
Mozilla makes sure Thunderbird's user base of just shy of 10 million people worldwide are never short of new features with updates being delivered at a similar rate to the Firefox browser it first grew out of.