when the recipient sees it, he must see the tables.
This is complete and utter garbage. Whether or not the recipient will see the tables will depend upon the mail client the recipient is using. If the mail client does not support HTML, or if the mail client is configured for plain text instead of HTML, you can send HTML (or XML or RTF or anything else you want to send) but the recipient will not see tables.
There is nothing to prevent you from creating HTML on a mainframe and sending it in an email as long as you follow the SMTP rules. Whether or not that email will be seen as HTML, however, is beyond your control and depends upon the mail client.