erp5_interface_post: preview of Mail Message uses Post content if it exists

bt5/erp5_interface_post/ActionTemplateItem/portal_types/Mail%20Message/mail_message_preview.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="ActionInformation" module="Products.CMFCore.ActionInformation"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>action</string> </key>
+            <value>
+              <persistent> <string encoding="base64">AAAAAAAAAAI=</string> </persistent>
+            </value>
+        </item>
+        <item>
+            <key> <string>categories</string> </key>
+            <value>
+              <tuple>
+                <string>action_type/object_view</string>
+              </tuple>
+            </value>
+        </item>
+        <item>
+            <key> <string>category</string> </key>
+            <value> <string>object_view</string> </value>
+        </item>
+        <item>
+            <key> <string>condition</string> </key>
+            <value>
+              <persistent> <string encoding="base64">AAAAAAAAAAM=</string> </persistent>
+            </value>
+        </item>
+        <item>
+            <key> <string>description</string> </key>
+            <value> <string>View to display if the portal type Internet Message Post is installed</string> </value>
+        </item>
+        <item>
+            <key> <string>icon</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>id</string> </key>
+            <value> <string>mail_message_preview</string> </value>
+        </item>
+        <item>
+            <key> <string>permissions</string> </key>
+            <value>
+              <tuple>
+                <string>View</string>
+              </tuple>
+            </value>
+        </item>
+        <item>
+            <key> <string>priority</string> </key>
+            <value> <float>10.0</float> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string>Preview</string> </value>
+        </item>
+        <item>
+            <key> <string>visible</string> </key>
+            <value> <int>1</int> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+  <record id="2" aka="AAAAAAAAAAI=">
+    <pickle>
+      <global name="Expression" module="Products.CMFCore.Expression"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>text</string> </key>
+            <value> <string>string:${object_url}/MailMessage_viewPreview</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+  <record id="3" aka="AAAAAAAAAAM=">
+    <pickle>
+      <global name="Expression" module="Products.CMFCore.Expression"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>text</string> </key>
+            <value> <string>python: getattr(context.getPortalObject(), \'internet_message_post_module\', None) is not None and portal.Base_checkPermission(\'internet_message_post_module\', \'View\')</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

bt5/erp5_interface_post/bt/template_action_path_list

@@ -6,3 +6,4 @@ Letter Post | preview_pdf
 Letter Post | view
 Letter | jump_to_letter_post
 Mail Message | jump_to_internet_message_post
+Mail Message | mail_message_preview
\ No newline at end of file