Answered via your support ticket. But in case anyone else happens upon this question and would like to know the answer:
You'll want to edit the mailer.php language file. The lines you're looking for are below. One is for HTML type emails and one is for regular.
$ubbt_lang['REG_CONTENT4_TEXT'] = " the following link:<br /><br /> %%VERIFY_URL%%";
$ubbt_lang['REG_CONTENT4_HTML'] = " <a href="%%VERIFY_URL%%">this link</a>.";
You can change those to something like:
$ubbt_lang['REG_CONTENT4_TEXT'] = " the following link:<br /><br /> %%VERIFY_URL%%.<br /><br />Your new paragraph can go here";
$ubbt_lang['REG_CONTENT4_HTML'] = " <a href="%%VERIFY_URL%%">this link</a>.<br /><br />Your new paragraph can go here.";
