comment_email
The comment_email tag is a single tag which is used to display the commenter’s email address, if entered at the time of posting. Used in a comments display form.
Comments Display Form with linked email and comment id
<txp:comment_message />
<p><small><a href="mailto:<txp:comment_email />">Email</a> |
<txp:comment_permlink><txp:comment_id /></txp:comment_permlink></small></p>
Other tags used: comment_id, comment_message, comment_permlink