In case any Mutt users are interested, here’s how this can be accomplished.

    # When replying to an email, use the To: address of the original email as the
    # From: address in the reply (requires that the To: address be recognised by
    # Mutt as being one of my alternate addresses).
    set reverse_name

    # Regex to let Mutt know what other email addresses are used by me.
    alternates @example

I had been thinking of writing a script to dynamically create a file of alternative addresses from /etc/aliases but this isn’t necessary. There’s no need to individually list all my alternate addresses as – currently – all [email protected] and [email protected] addresses are me so it is enough to just match the `@example` regular expression.

Edit: For composing a new message (not a reply), I have this set:

    # When composing a message, edit the headers along with the message body.
    # This should make it easier to see that the correct From address is being used
    # and to fix this if necessary.
    set edit_headers