To je takova pitomost v E2007, taky jsem kdysi dlouho hledal.
http://exchangeshell.wordpress.com/2009/08/31/cannot-get-external-out-of-office-oof-working-with-exchange-2007/
spustit EMS Get-remotedomain | fl
zkontrolovat typ AllowedOOFType - po instalaci je nastaveno na External.
To by fungovalo, pokud by se Mimo kancelar nastavovalo Outlookem 2007 a vyssim. Pokud se pouzivají i starsi klienti, musi byt typ ExternalLegacy
opravit spustenim EMS Set-remotedomain -identity default -AllowedOOFType externallegacy