If we would like to understand, say, Benjamin Franklin: what is an excellent source to the thoughts and reasonings of this person? His correspondence, as documented for example in The private correspondence of Benjamin Franklin. Why is this the case? Because we take great care in formulating our thoughts and ideas when we try to explain them to others. As paper has been replaced by electronic communications - by e-mail, in fact - inboxes become our main correspondence archive. What a petty, then, that our inboxes are small and short-lived. This is why the attribute reliable is so important in design and implementation of mailxel.
