As reported in the forums (example):

I use LimeSurvey as an application form. I need to send it to several people who can review the application (i.e. personel@company.com, manager@company.com, recruiting@company.com, archive@company.com). I put these emailadresses in the admin email field under "general survey settings", like this: personel@company.com;manager@company.com;recruiting@company.com;archive@company.com Every address gets the message, but in the email it says From: admin personel@company.com;manager@company.com;recruiting@company.com;archive@company.com ... which goes into the "unwanted email" folder. You cannot add this to a whitelist, as it isn't a valid e-mailadress.