rmail-dont-reply-to-names

rmail-dont-reply-to-names is a variable defined in `rmail.el'.
Its value is

nil

• This variable is an alias for `mail-dont-reply-to-names'.
• This variable is obsolete since 24.1;
  use `mail-dont-reply-to-names' instead.

Documentation:
Regexp specifying addresses to prune from a reply message.
If this is nil, it is set the first time you compose a reply, to
a value which excludes your own email address.

Matching addresses are excluded from the CC field in replies, and
also the To field, unless this would leave an empty To field.

You can customize this variable.