explicitly call incomingmail default methods. Could be replaced by a more generic method finding field default_value methods...

setup.py

@@ -42,6 +42,7 @@ setup(name='collective.dms.batchimport',
       install_requires=[
           'setuptools',
           'collective.dms.basecontent',
+          'collective.dms.mailcontent',
           'collective.z3cform.datagridfield',
           'five.grok',
       ],

src/collective/dms/batchimport/batchimport.py

@@ -16,10 +16,10 @@ from plone.registry.interfaces import IRegistry
 from plone.i18n.normalizer.interfaces import IIDNormalizer
 from collective.z3cform.datagridfield import DataGridFieldFactory
 from collective.z3cform.datagridfield.registry import DictRow
+from collective.dms.mailcontent.dmsmail import internalReferenceIncomingMailDefaultValue, receptionDateDefaultValue
 
 from plone.app.registry.browser import controlpanel
 
-
 from . import _
 
 log = logging.getLogger('collective.dms.batchimport')
@@ -168,6 +168,10 @@ class BatchImporter(BrowserView):
         else:
             document_title = os.path.splitext(filename)[0].split('-', 1)[1]
 
+        if portal_type == 'dmsincomingmail':
+            metadata['internal_reference_no'] = internalReferenceIncomingMailDefaultValue(self)
+            metadata['reception_date'] = receptionDateDefaultValue(self)
+
         log.info("creating the document for real (%s)" % document_id)
         folder.invokeFactory(portal_type, id=document_id, title=document_title,
                         **metadata)

src/collective/dms/batchimport/configure.zcml

@@ -8,6 +8,7 @@
 
   <include package="five.grok" />
   <include package="collective.z3cform.datagridfield" />
+  <include package="collective.dms.mailcontent" />
 
   <grok:grok package="." />
 

src/collective/dms/batchimport/profiles/default/metadata.xml

@@ -1,4 +1,7 @@
 <?xml version="1.0"?>
 <metadata>
   <version>0001</version>
+  <dependencies>
+    <dependency>profile-collective.dms.mailcontent:default</dependency>
+  </dependencies>
 </metadata>