Thunderbird.
The new version of my favourite email client application has arrived. New features include a spell checker that underlines misspelt words in red like a school teacher! Yeah! Take that MS word. Anyway its got loads of other features including privacy support (it doesn’t fetch remote images in emails without your permission), integrated RSS reader (so you can subscribe to my feeds 
), multiple account support including support for one global inbox and more.
Size= ~6.5MB