Many email systems add an Apparently-To header to messages that only have BCC recipients. This header, if added, will list all of your recipients to your message anyway. To avoid this, you should add at least one To: or CC: recipient.
Posta-programa askok Apparently-To goiburua gehitzen diete BCC hartzaileak soilik dituzten mezuei. Goiburu hori gehituz gero, hartzaile guztiak zerrendatuko dira mezuan. Hori gerta ez dadin, gutxienez hartzaile bat zehaztu behar da Nori: edo Cc: hartzailean.