diff --git a/messageviewer/src/messagepartthemes/default/defaultrenderer.h b/messageviewer/src/messagepartthemes/default/defaultrenderer.h
--- a/messageviewer/src/messagepartthemes/default/defaultrenderer.h
+++ b/messageviewer/src/messagepartthemes/default/defaultrenderer.h
@@ -22,6 +22,12 @@
 
 #include <QSharedPointer>
 
+#include <functional>
+
+namespace KMime {
+class Message;
+}
+
 namespace MimeTreeParser {
 class MessagePart;
 typedef QSharedPointer<MessagePart> MessagePartPtr;
@@ -47,6 +53,7 @@
     void setShowSignatureDetails(bool showSignatureDetails);
     void setLevelQuote(int levelQuote);
     void setHtmlLoadExternal(bool htmlLoadExternal);
+    void setCreateMessageHeader(std::function<QString(KMime::Message*)>);
     void render(const MimeTreeParser::MessagePartPtr &msgPart, HtmlWriter *writer);
 private:
     DefaultRendererPrivate *d;
diff --git a/messageviewer/src/messagepartthemes/default/defaultrenderer.cpp b/messageviewer/src/messagepartthemes/default/defaultrenderer.cpp
--- a/messageviewer/src/messagepartthemes/default/defaultrenderer.cpp
+++ b/messageviewer/src/messagepartthemes/default/defaultrenderer.cpp
@@ -380,7 +380,7 @@
     block.setProperty("link",
                       mp->nodeHelper()->asHREF(mp->message().data(), QStringLiteral("body")));
 
-    c.insert(QStringLiteral("msgHeader"), mp->source()->createMessageHeader(mp->message().data()));
+    c.insert(QStringLiteral("msgHeader"), mCreateMessageHeader(mp->message().data()));
     c.insert(QStringLiteral("content"), QVariant::fromValue<GrantleeCallback>([this, mp, htmlWriter](Grantlee::OutputStream *) {
         renderSubParts(mp, htmlWriter);
     }));
@@ -1117,6 +1117,11 @@
     d->mHtmlLoadExternal = htmlLoadExternal;
 }
 
+void DefaultRenderer::setCreateMessageHeader(std::function<QString(KMime::Message*)> createMessageHeader)
+{
+    d->mCreateMessageHeader = createMessageHeader;
+}
+
 void DefaultRenderer::render(const MimeTreeParser::MessagePart::Ptr &msgPart, HtmlWriter *writer)
 {
     d->mMsgPart = msgPart;
diff --git a/messageviewer/src/messagepartthemes/default/defaultrenderer_p.h b/messageviewer/src/messagepartthemes/default/defaultrenderer_p.h
--- a/messageviewer/src/messagepartthemes/default/defaultrenderer_p.h
+++ b/messageviewer/src/messagepartthemes/default/defaultrenderer_p.h
@@ -70,6 +70,8 @@
     CSSHelperBase *mCSSHelper = nullptr;
     const MessagePartRendererFactory *mRendererFactory = nullptr;
     const AttachmentStrategy *mAttachmentStrategy = nullptr;
+    std::function<QString(KMime::Message*)> mCreateMessageHeader;
+
     int mLevelQuote = 1;
 
     bool mShowEmoticons = false;
diff --git a/messageviewer/src/viewer/objecttreeemptysource.h b/messageviewer/src/viewer/objecttreeemptysource.h
--- a/messageviewer/src/viewer/objecttreeemptysource.h
+++ b/messageviewer/src/viewer/objecttreeemptysource.h
@@ -41,7 +41,7 @@
     MimeTreeParser::Util::HtmlMode preferredMode() const override;
     void setAllowDecryption(bool allowDecryption);
     const QTextCodec *overrideCodec() override;
-    QString createMessageHeader(KMime::Message *message) override;
+    virtual QString createMessageHeader(KMime::Message *message);
     bool autoImportKeys() const override;
 
     const MimeTreeParser::BodyPartFormatterFactory *bodyPartFormatterFactory() override;
diff --git a/messageviewer/src/viewer/objecttreeemptysource.cpp b/messageviewer/src/viewer/objecttreeemptysource.cpp
--- a/messageviewer/src/viewer/objecttreeemptysource.cpp
+++ b/messageviewer/src/viewer/objecttreeemptysource.cpp
@@ -151,6 +151,7 @@
 
     auto renderer = DefaultRenderer(cssHelper());
     renderer.setAttachmentStrategy(attachmentStrategy());
+    renderer.setCreateMessageHeader(std::bind(&EmptySource::createMessageHeader, this, std::placeholders::_1));
     renderer.setHtmlLoadExternal(htmlLoadExternal());
     renderer.setIsPrinting(isPrinting());
     renderer.setLevelQuote(levelQuote());
diff --git a/mimetreeparser/autotests/setupenv.h b/mimetreeparser/autotests/setupenv.h
--- a/mimetreeparser/autotests/setupenv.h
+++ b/mimetreeparser/autotests/setupenv.h
@@ -88,12 +88,6 @@
         return nullptr;
     }
 
-    QString createMessageHeader(KMime::Message *message) override
-    {
-        Q_UNUSED(message);
-        return QString(); //do nothing
-    }
-
     void render(const MessagePart::Ptr &msgPart, bool showOnlyOneMimePart) override
     {
         Q_UNUSED(msgPart);
diff --git a/mimetreeparser/src/interfaces/objecttreesource.h b/mimetreeparser/src/interfaces/objecttreesource.h
--- a/mimetreeparser/src/interfaces/objecttreesource.h
+++ b/mimetreeparser/src/interfaces/objecttreesource.h
@@ -62,8 +62,6 @@
     /** The override codec that should be used for the mail */
     virtual const QTextCodec *overrideCodec() = 0;
 
-    virtual QString createMessageHeader(KMime::Message *message) = 0;
-
     /** should keys be imported automatically **/
     virtual bool autoImportKeys() const = 0;