diff --git a/welco/sources/mail/templates/welco/mail_summary.html b/welco/sources/mail/templates/welco/mail_summary.html
index cc1abd2..7ba521a 100644
--- a/welco/sources/mail/templates/welco/mail_summary.html
+++ b/welco/sources/mail/templates/welco/mail_summary.html
@@ -1,6 +1,10 @@
 {% load i18n %}
 {% if object.post_date %}
-<p>{% trans "Post Date:" %} {{object.post_date}}</p>
+<p class="post-date">{% trans "Post Date:" %} {{object.post_date}}</p>
+{% endif %}
+
+{% if object.registered_mail_number %}
+<p class="registered-mail-number">{% trans "Registered Mail Number:" %} {{object.registered_mail_number}}</p>
 {% endif %}
 
 <p class="thumbnail">