Thank you for pointing me to the filtering... and the manual... i must admit i should have looked there first
Anyway i sorted my problem. The solution was (if anyone's interested):
ContactCollection contacts = new ContactCollection();
IPredicate filterElement = (ContactFields.IsBookingManager == 1);
contacts.GetMulti(filterElement);
foreach (ContactEntity contact in contacts)
{
objEmail.To.Add(contact.Email);
}
Thank you again for your help and quick answer!