This doesn't seem so crazy. Google deletes emails after a few months for rank/file and 6 months for executives for the sake of avoiding lawsuits as well.
> ... after a few months for rank/file and 6 months for executives
What's your source for this? I can easily believe they delete emails. But I would expect them to be subject to various laws about email retention, and those laws typically require companies to hold on to emails for years.
