Many emails now being created, and thus potentially archived by libraries, are the contemporary equivalent not of paper letters, but of phone calls - which, with few exceptions, were unrecorded, and really were lost to history.
... In terms of digital literary archives, one of the lessons for today's archivists is that so-called e-manuscripts are highly unstable, and need early curatorial intervention to secure them against the threats of technological obsolescence. This means that the writers involved become increasingly aware of interest in their papers, and for novelist Jonathan Franzen, this changes everything: 'Unfortunately, I think that once writers become self-conscious about preserving archival material, the game is over...I also don't see how you resist the temptation to select material that suggests the most flattering narratives. And not just select, but actively create!' ..." - from the Source: http://www.huffingtonpost.co.uk