1. Odpalić konsole powershell Exchange 2010
2. Przejść do katalogu %PROGRAMFILES%\Microsoft\Exchange Server\V14\Scripts
3. Uruchomić .\ResetSearchIndex.ps1 -force -all

Źródło: http://www.sheenaustin.com/2010/11/11/exchange-2010-search-reset-search-index/