AirDrop on ios not recognising contacts
I have an Apple ID which is an outlook address. However I use an icloud address for everything else and it is registered as alternate email address on my Apple ID. However when my contacts try to airdrop me they do not discover me unless they add my outlook address to their contacts or enable all users. Neither is really acceptable, so can anyone help please.
Many thanks.
iPhone 5, iOS 7.0.2