In the mail view you can choose to Reply, Reply All, or Forward:
- Reply — Reply to the sender only.
- Reply All — Reply to the sender and everyone else in the To and Cc fields. People who were Bcc'd are not included: a received email does not reveal them, so no mail app can reply to them.
- Forward — Send a copy of the email to other recipients.
Choosing which one the reply button does
If replying always includes everyone — or never does, when you would rather it did — that is a setting rather than a quirk. Go to Settings | Global Settings | Advanced Features | Default Reply Action and pick Reply or Reply All. It decides what the reply button does on its own; the other option stays available, so nothing is taken away either way.
The setting is app-wide rather than per account, and it does not alter existing threads — only what happens the next time you reply.
