Returns a table of mbox message data, with "sender/recipient" pairs as rows/observations.

        .. note::

            Rows may have a recipient from either "TO" or "CC". SendType column specifies this for each row.

        .. note::

            drop_collections is not available for this method, since there are no meaningful collections to keep.

        :return: pandas.DataFrame

def sends(self):
        """
        Returns a table of mbox message data, with "sender/recipient" pairs as rows/observations.

        .. note::

            Rows may have a recipient from either "TO" or "CC". SendType column specifies this for each row.

        .. note::

            drop_collections is not available for this method, since there are no meaningful collections to keep.

        :return: pandas.DataFrame
        """
        # Expand on each "to" field
        on_to_df = self.expand_on('From', 'To', rename1='From', rename2='Recipient')
        on_cc_df = self.expand_on('From', 'Cc', rename1='From', rename2='Recipient')

        # Specify how it was sent
        on_to_df['SendType'] = 'To'
        on_cc_df['SendType'] = 'Cc'

        # Combine dataframes
        output_df = pd.concat([on_to_df, on_cc_df])

        return self._drop_collections(output_df)