Hide the list of the recipients' addresses for an email message

When you send an email to several people, the "To:" or "For:" field should preferably feature a single address (your secondary address, for example), and in the "BCC:" or "CCI:" field, you may include your various correspondents' addresses.

These "BCC” or "CCI" fields ("blind carbon copy" and "copie carbone invisible" respectively) will make your recipients believe that they are the only person to receive the email, or at least will hide the addresses from other people, avoiding the propagation of spam in general and providing a welcome confidentiality.

In kMail, you can enable these fields at the top right of the message window:

the "Cc" field indicates the recipients who will receive a copy of the email without hiding their addresses!