diff --git a/src/email.c b/src/email.c
new file mode 100644
index 00000000..fa07e0da
--- /dev/null
+++ b/src/email.c
@@ -0,0 +1,14 @@
+#include "email.h"
+
+PEP_STATUS email_sendto(PEP_SESSION session, const message *msg)
+{
+
+    return PEP_STATUS_OK;
+}
+
+PEP_STATUS email_readnext(PEP_SESSION session, message **msg, PEP_transport_t **via)
+{
+
+    return PEP_STATUS_OK;
+}
+
diff --git a/src/email.h b/src/email.h
new file mode 100644
index 00000000..e7971b5f
--- /dev/null
+++ b/src/email.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#include "transport.h"
+
+PEP_STATUS email_sendto(PEP_SESSION session, const message *msg);
+PEP_STATUS email_readnext(PEP_SESSION session, message **msg, PEP_transport_t **via);
diff --git a/src/trans_auto.c b/src/trans_auto.c
new file mode 100644
index 00000000..753430bd
--- /dev/null
+++ b/src/trans_auto.c
@@ -0,0 +1,13 @@
+#include "trans_auto.h"
+
+PEP_STATUS auto_sendto(PEP_SESSION session, const message *msg)
+{
+
+    return PEP_STATUS_OK;
+}
+
+PEP_STATUS auto_readnext(PEP_SESSION session, message **msg, PEP_transport_t **via)
+{
+
+    return PEP_STATUS_OK;
+}
diff --git a/src/trans_auto.h b/src/trans_auto.h
new file mode 100644
index 00000000..1bfa62f9
--- /dev/null
+++ b/src/trans_auto.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#include "transport.h"
+
+PEP_STATUS auto_sendto(PEP_SESSION session, const message *msg);
+PEP_STATUS auto_readnext(PEP_SESSION session, message **msg, PEP_transport_t **via);
diff --git a/src/transport.c b/src/transport.c
index 573c990c..0e4742e3 100644
--- a/src/transport.c
+++ b/src/transport.c
@@ -5,6 +5,8 @@
 
 PEP_STATUS init_transport_system(PEP_SESSION session)
 {
+    assert(session);
+
     pEpSession *_session = (pEpSession *) session;
     PEP_transport_t* transports = _session->transports;
 
@@ -18,11 +20,14 @@ PEP_STATUS init_transport_system(PEP_SESSION session)
 
 void release_transport_system(PEP_SESSION session)
 {
+    assert(session);
     // nothing yet
 }
 
 pEp_identity *identity_dup(const pEp_identity *src)
 {
+    assert(src);
+
     pEp_identity *dup = new_identity(src->address, src->fpr, src->user_id, src->username);
     assert(dup);
     if (dup == NULL)
diff --git a/src/transport.h b/src/transport.h
index 173ab25d..a69d87bd 100644
--- a/src/transport.h
+++ b/src/transport.h
@@ -90,6 +90,8 @@ struct _PEP_transport_t {
     uint8_t id;
     sendto_t sendto;
     readnext_t readnext;
+    bool long_message_supported;
+    msg_format native_format;
 };
 
 typedef uint64_t transports_mask;