Mask email address of recipients in forwarded email
All to often improper email etiquette is used when forwarding an email to a mixed group of recipients that don't know one another and the sender does not use the BCC but instead uses the TO or CC revealing everyone's email address. One draw back of the BCC is the recipients don't not know who received the forwarded email and thus do not know if forwarding the email to certain people will result in duplicate emails to those recipients. However, this could be solved by if the TO and CC fields would just list the recipients names (or whatever is saved in the sender's contacts) without divulging their respective email address. If any recipient wants to forward the email on "to the people they know" then they will more than likely already have those email addresses in their contacts, and thus preserving the privacy (email addresses) of the people not known by the others.

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Tunafish commented
Good idea that may also help reduce spam.
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Stian commented
Agree. BCC should be default. One can always use CC if that's needed.