email_log: Show reply_to address if present.

templates/zerver/email.html

@@ -1,4 +1,11 @@
 <h4>From: {{ from_email }}</h4>
+{% if reply_to %}
+<h4>Reply To:
+    {% for email in reply_to %}
+    {{ email }}&nbsp;
+    {% endfor %}
+</h4>
+{% endif %}
 <h4>To:
     {% for recipient in recipients %}
     {{ recipient }}&nbsp;

zproject/email_backends.py

@@ -67,6 +67,7 @@ class EmailLogBackEnd(BaseEmailBackend):
         context = {
             'subject': email.subject,
             'from_email': email.from_email,
+            'reply_to': email.reply_to,
             'recipients': email.to,
             'body': email.body,
             'html_message': html_message,