diff --git a/lms/djangoapps/instructor/views/legacy.py b/lms/djangoapps/instructor/views/legacy.py
index 0acf82e9563c..d3ef8498a8c7 100644
--- a/lms/djangoapps/instructor/views/legacy.py
+++ b/lms/djangoapps/instructor/views/legacy.py
@@ -743,7 +743,7 @@ def getdat(u):
         else:
             # If sending the task succeeds, deliver a success message to the user.
             if email_to_option == "all":
-                email_msg = '<div class="msg msg-confirm"><p class="copy">Your email was successfully queued for sending. Please note that for large public classes (~10k), it may take 1-2 hours to send all emails.</p></div>'
+                email_msg = '<div class="msg msg-confirm"><p class="copy">Your email was successfully queued for sending. Please note that for large classes, it may take up to an hour (or more, if other courses are simultaneously sending email) to send all emails.</p></div>'
             else:
                 email_msg = '<div class="msg msg-confirm"><p class="copy">Your email was successfully queued for sending.</p></div>'
 
diff --git a/lms/static/coffee/src/instructor_dashboard/send_email.coffee b/lms/static/coffee/src/instructor_dashboard/send_email.coffee
index b9500411699d..7fc839cca6bf 100644
--- a/lms/static/coffee/src/instructor_dashboard/send_email.coffee
+++ b/lms/static/coffee/src/instructor_dashboard/send_email.coffee
@@ -35,7 +35,7 @@ class SendEmail
           send_to = gettext("everyone who is staff or instructor on this course")
         else
           send_to = gettext("ALL (everyone who is enrolled in this course as student, staff, or instructor)")
-          success_message = gettext("Your email was successfully queued for sending.  Please note that for large public classes (~10k), it may take 1-2 hours to send all emails.")
+          success_message = gettext("Your email was successfully queued for sending. Please note that for large classes, it may take up to an hour (or more, if other courses are simultaneously sending email) to send all emails.")
         subject = gettext(@$subject.val())
         confirm_message = gettext("You are about to send an email titled \"#{subject}\" to #{send_to}.  Is this OK?")
         if confirm confirm_message
diff --git a/lms/templates/courseware/instructor_dashboard.html b/lms/templates/courseware/instructor_dashboard.html
index 61c073aa01ca..c2488694225c 100644
--- a/lms/templates/courseware/instructor_dashboard.html
+++ b/lms/templates/courseware/instructor_dashboard.html
@@ -539,11 +539,17 @@ <h2>${_("Batch Enrollment")}</h2>
     </ul>
 
     <div class="submit-email-action">
-      ${_("Please try not to email students more than once a day. Important things to consider before sending:")}
+      <p class="copy">${_("Please try not to email students more than once per week. Important things to consider before sending:")}</p>
       <ul class="list-advice">
         <li class="item">${_("Have you read over the email to make sure it says everything you want to say?")}</li>
-        <li class="item">${_("Have you sent the email to yourself first to make sure you're happy with how it's displayed?")}</li>
+        <li class="item">${_("Have you sent the email to yourself first to make sure you're happy with how it's displayed, and that embedded links and images work properly?")}</li>
       </ul>
+      <div class="submit-email-warning">
+	<p class="copy"><span style="color: red;"><b>${_("CAUTION!")}</b></span>
+	  ${_("Once the 'Send Email' button is clicked, your email will be queued for sending.")}
+	<b>${_("A queued email CANNOT be cancelled.")}</b></p>
+      </div>
+      <br />
       <input type="submit" name="action" value="Send email">
     </div>
     <script type="text/javascript">
@@ -556,6 +562,7 @@ <h2>${_("Batch Enrollment")}</h2>
       });
     </script>
 
+    <br />
     <p>These email actions run in the background, and status for active email tasks will appear in a table below.
        To see status for all bulk email tasks submitted for this course, click on this button:
     </p>
diff --git a/lms/templates/instructor/instructor_dashboard_2/send_email.html b/lms/templates/instructor/instructor_dashboard_2/send_email.html
index 8a5608e7c52f..0ff0360e91c0 100644
--- a/lms/templates/instructor/instructor_dashboard_2/send_email.html
+++ b/lms/templates/instructor/instructor_dashboard_2/send_email.html
@@ -40,12 +40,18 @@ <h2> ${_("Send Email")} </h2>
   </li>
   </ul>
  <div class="submit-email-action">
-  ${_("Please try not to email students more than once a day. Before sending your email, consider:")}
+  <p class="copy">${_("Please try not to email students more than once per week. Before sending your email, consider:")}</p>
   <ul class="list-advice">
    <li class="item">${_("Have you read over the email to make sure it says everything you want to say?")}</li>
-   <li class="item">${_("Have you sent the email to yourself first to make sure you're happy with how it's displayed?")}</li>
+   <li class="item">${_("Have you sent the email to yourself first to make sure you're happy with how it's displayed, and that embedded links and images work properly?")}</li>
   </ul>
  </div>
+ <div class="submit-email-warning">
+   <p class="copy"><span style="color: red;"><b>${_("CAUTION!")}</b></span>
+     ${_("Once the 'Send Email' button is clicked, your email will be queued for sending.")}
+   <b>${_("A queued email CANNOT be cancelled.")}</b></p>
+</div>
+ <br />
   <input type="button" name="send" value="${_("Send Email")}" data-endpoint="${ section_data['send_email'] }" >
   <div class="request-response-error"></div>
 </div>