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There are is also a known issue with Apple Mail for users with tons and tons of emails. Users with historical emails going back years should consider archiving emails older than say 5 years and taking those emails permanently offline. Both the size of emails and sheer quantity (hundreds of thousands) can cause Apple Mail to pinwheel or not properly display or locate those emails in searches. Sometimes it can take a really long time for those emails to come up. For the Exchange email system such as the one we now use here at MIT, the only client program that can successfully handle this kind of quantity volume (hundreds of thousands) of emails is Microsoft Outlook 2010 or later on Windows 7 or 8.
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