Displays the comment author's email address, as a mailto link. An email address must be provided if "User must fill out name and email" is enabled under Discussion Options. This tag must be within The Loop, or a comment loop.
Note: Displaying email addresses is not recommended, as it provides spam collection tools the opportunity to cull them from your site.
Use get_comment_author_email_link to retrieve the value.
<?php comment_author_email_link('linktext', 'before', 'after'); ?>
email: <?php comment_author_email_link(); ?><br />
Displays comment author's email link as text string Email Comment Author and adds arrows before and after the link to style it.
<?php comment_author_email_link('Email Comment Author', ' > ', ' < '); ?>