diff --git a/CHANGES.rst b/CHANGES.rst
index e7f6da9..789ef5f 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -14,7 +14,13 @@ New features:
 
 Bug fixes:
 
-- *add item here*
+- Reset the required setting of the author_email widget each time.
+  Otherwise, the email field might get set to required when an
+  anonymous user visits, and then remain required when an
+  authenticated user visits, making it impossible for an authenticated
+  user to fill in the form without validation error.  Or when in the
+  control panel the field is set as not required anymore, that change
+  would have no effect until the instance was restarted.  [maurits]
 
 
 2.4.14 (2016-06-06)
diff --git a/plone/app/discussion/browser/comments.py b/plone/app/discussion/browser/comments.py
index a1c80af..7d9695c 100644
--- a/plone/app/discussion/browser/comments.py
+++ b/plone/app/discussion/browser/comments.py
@@ -87,6 +87,20 @@ class CommentForm(extensible.ExtensibleForm, form.Form):
         self.widgets['in_reply_to'].mode = interfaces.HIDDEN_MODE
         self.widgets['text'].addClass('autoresize')
         self.widgets['user_notification'].label = _(u'')
+        # Reset widget field settings to their defaults, which may be changed
+        # further on.  Otherwise, the email field might get set to required
+        # when an anonymous user visits, and then remain required when an
+        # authenticated user visits, making it impossible for an authenticated
+        # user to fill in the form without validation error.  Or when in the
+        # control panel the field is set as not required anymore, that change
+        # would have no effect until the instance was restarted.  Note that the
+        # widget is new each time, but the field is the same item in memory as
+        # the previous time.
+        self.widgets['author_email'].field.required = False
+        # The widget is new, but its 'required' setting is based on the
+        # previous value on the field, so we need to reset it here.  Changing
+        # the field in updateFields does not help.
+        self.widgets['author_email'].required = False
 
         # Rename the id of the text widgets because there can be css-id
         # clashes with the text field of documents when using and overlay
diff --git a/plone/app/discussion/tests/functional_test_comments.txt b/plone/app/discussion/tests/functional_test_comments.txt
index ccdb4ff..6aa6b81 100644
--- a/plone/app/discussion/tests/functional_test_comments.txt
+++ b/plone/app/discussion/tests/functional_test_comments.txt
@@ -479,3 +479,60 @@ Make sure the edit was successful.
 
     >>> 'Lorem ipsum' in browser.contents
     True
+
+
+Require anonymous email
+-----------------------
+
+Edit the control panel.
+
+    >>> browser.open(portal_url + '/logout')
+    >>> browser.open(portal_url + '/login_form')
+    >>> browser.getControl(name='__ac_name').value = 'admin'
+    >>> browser.getControl(name='__ac_password').value = 'secret'
+    >>> browser.getControl(name='submit').click()
+    >>> browser.open(portal_url+'/@@discussion-controlpanel')
+    >>> browser.getControl(name='form.widgets.anonymous_email_enabled:list').value = [True]
+    >>> browser.getControl(name='form.buttons.save').click()
+    >>> browser.open(portal_url + '/logout')
+
+Post an anonymous comment without setting the email.
+
+    >>> unprivileged_browser.open(urldoc1)
+    >>> unprivileged_browser.getControl(name='form.widgets.text').value = "This is an anonymous comment without email"
+    >>> unprivileged_browser.getControl(name='form.buttons.comment').click()
+    >>> 'Required input is missing' in unprivileged_browser.contents
+    True
+
+Try again.
+
+    >>> unprivileged_browser.getControl(name='form.widgets.text').value = "This is an anonymous comment with email"
+    >>> unprivileged_browser.getControl(name='form.widgets.author_email').value = "email@example.org"
+    >>> unprivileged_browser.getControl(name='form.buttons.comment').click()
+    >>> 'Required input missing' in unprivileged_browser.contents
+    False
+    >>> 'Your comment awaits moderator approval' in unprivileged_browser.contents
+    True
+
+Posting as member should still work.  Especially it should not
+complain about missing input for an invisible author_email field.
+Login as user 'jim'.
+
+    >>> browser_member.open(portal_url + '/login_form')
+    >>> browser_member.getControl(name='__ac_name').value = 'jim'
+    >>> browser_member.getControl(name='__ac_password').value = 'secret'
+    >>> browser_member.getControl(name='submit').click()
+
+Post a comment as user jim.
+
+    >>> browser_member.open(urldoc1)
+    >>> browser_member.getControl(name='form.widgets.text').value = "Use the ZODB, Luke!"
+    >>> submit = browser_member.getControl(name='form.buttons.comment')
+    >>> submit.click()
+
+Check if there are no validation errors.
+
+    >>> 'Required input missing' in browser_member.contents
+    False
+    >>> 'Your comment awaits moderator approval' in browser_member.contents
+    True