Since HEAT 2014.3.1, it is possible to reply an email (Reply button). Usually, the EmailBody field is configured as an HTML Editor field in the Journal.Email.New form, but if the email that we are going to reply is in Plain Text format, the HTML toolbar is not going to be shown, in a similar way that when answering a Plain Text email with a regular email client as Outlook.
For using the new HTML capabilities, we should being receiving the emails in HTML format (when the email is HTML formatted). Please open the AdminUI of the production tenant and open the following option:
Configure >> Email Configuration >> Servers >> Servers
Modify the "Store Journal Email As" to HTML
Once the incoming email is in HTML format, the Reply option will allow you to write the email using the HTML toolbar (if the original message was written in HTML format).