diff --git a/src/solanaceae/message3/message_serializer.cpp b/src/solanaceae/message3/message_serializer.cpp
index 253b62b..5d2baa7 100644
--- a/src/solanaceae/message3/message_serializer.cpp
+++ b/src/solanaceae/message3/message_serializer.cpp
@@ -18,24 +18,44 @@ static Contact3 findContactByID(Contact3Registry& cr, const std::vector<uint8_t>
 	return entt::null;
 }
 
+nlohmann::json MessageSerializerNJ::serlContactByID(Contact3 c) const {
+	if (!cr.valid(c)) {
+		// while this is invalid registry state, it is valid serialization
+		std::cerr << "MSC warning: encountered invalid contact\n";
+		return nullptr;
+	}
+
+	if (!cr.all_of<Contact::Components::ID>(c)) {
+		// unlucky, this contact is purely ephemeral
+		std::cerr << "MSC warning: encountered contact without ID\n";
+		return nullptr;
+	}
+
+	return nlohmann::json::binary(cr.get<Contact::Components::ID>(c).data);
+}
+
+Contact3 MessageSerializerNJ::deserlContactByID(const nlohmann::json& j) {
+	std::vector<uint8_t> id;
+	if (j.is_binary()) {
+		id = j.get_binary();
+	} else {
+		j["bytes"].get_to(id);
+	}
+
+	Contact3 other_c = findContactByID(cr, id);
+	if (!cr.valid(other_c)) {
+		// create sparse contact with id only
+		other_c = cr.create();
+		cr.emplace_or_replace<Contact::Components::ID>(other_c, id);
+	}
+
+	return other_c;
+}
+
 template<>
 bool MessageSerializerNJ::component_get_json<Message::Components::ContactFrom>(MessageSerializerNJ& msc, const Handle h, nlohmann::json& j) {
 	const Contact3 c = h.get<Message::Components::ContactFrom>().c;
-	if (!msc.cr.valid(c)) {
-		// while this is invalid registry state, it is valid serialization
-		j = nullptr;
-		std::cerr << "MSC warning: encountered invalid contact\n";
-		return true;
-	}
-
-	if (!msc.cr.all_of<Contact::Components::ID>(c)) {
-		// unlucky, this contact is purely ephemeral
-		j = nullptr;
-		std::cerr << "MSC warning: encountered contact without ID\n";
-		return true;
-	}
-
-	j = nlohmann::json::binary(msc.cr.get<Contact::Components::ID>(c).data);
+	j = msc.serlContactByID(c);
 
 	return true;
 }
@@ -48,21 +68,7 @@ bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components:
 		return true;
 	}
 
-	std::vector<uint8_t> id;
-	if (j.is_binary()) {
-		id = j.get_binary();
-	} else {
-		j["bytes"].get_to(id);
-	}
-
-	Contact3 other_c = findContactByID(msc.cr, id);
-	if (!msc.cr.valid(other_c)) {
-		// create sparse contact with id only
-		other_c = msc.cr.create();
-		msc.cr.emplace_or_replace<Contact::Components::ID>(other_c, id);
-	}
-
-	h.emplace_or_replace<Message::Components::ContactFrom>(other_c);
+	h.emplace_or_replace<Message::Components::ContactFrom>(msc.deserlContactByID(j));
 
 	// TODO: should we return false if the contact is unknown??
 	return true;
@@ -71,21 +77,7 @@ bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components:
 template<>
 bool MessageSerializerNJ::component_get_json<Message::Components::ContactTo>(MessageSerializerNJ& msc, const Handle h, nlohmann::json& j) {
 	const Contact3 c = h.get<Message::Components::ContactTo>().c;
-	if (!msc.cr.valid(c)) {
-		// while this is invalid registry state, it is valid serialization
-		j = nullptr;
-		std::cerr << "MSC warning: encountered invalid contact\n";
-		return true;
-	}
-
-	if (!msc.cr.all_of<Contact::Components::ID>(c)) {
-		// unlucky, this contact is purely ephemeral
-		j = nullptr;
-		std::cerr << "MSC warning: encountered contact without ID\n";
-		return true;
-	}
-
-	j = nlohmann::json::binary(msc.cr.get<Contact::Components::ID>(c).data);
+	j = msc.serlContactByID(c);
 
 	return true;
 }
@@ -98,21 +90,65 @@ bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components:
 		return true;
 	}
 
-	std::vector<uint8_t> id;
-	if (j.is_binary()) {
-		id = j.get_binary();
-	} else {
-		j["bytes"].get_to(id);
-	}
-
-	Contact3 other_c = findContactByID(msc.cr, id);
-	if (!msc.cr.valid(other_c)) {
-		// create sparse contact with id only
-		other_c = msc.cr.create();
-		msc.cr.emplace_or_replace<Contact::Components::ID>(other_c, id);
-	}
-
-	h.emplace_or_replace<Message::Components::ContactTo>(other_c);
+	h.emplace_or_replace<Message::Components::ContactTo>(msc.deserlContactByID(j));
+
+	// TODO: should we return false if the contact is unknown??
+	return true;
+}
+
+template<>
+bool MessageSerializerNJ::component_get_json<Message::Components::ReceivedBy>(MessageSerializerNJ& msc, const Handle h, nlohmann::json& j) {
+	const auto& comp = h.get<Message::Components::ReceivedBy>();
+	if (comp.ts.empty()) {
+		// empty array
+		j = nlohmann::json::array();
+		return true;
+	}
+
+	for (const auto& [c, v] : comp.ts) {
+		if (!msc.cr.valid(c) || !msc.cr.all_of<Contact::Components::ID>(c)) {
+			// while this is invalid registry state, it is valid serialization
+			// we just skip this contact entirely and drop the time
+			std::cerr << "MSC warning: encountered invalid contact / contact without ID\n";
+			continue;
+		}
+		auto& new_entry = j.emplace_back(nlohmann::json::array());
+		new_entry.emplace_back(msc.serlContactByID(c));
+		new_entry.emplace_back(v);
+	}
+
+	return true;
+}
+
+template<>
+bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components::ReceivedBy>(MessageSerializerNJ& msc, Handle h, const nlohmann::json& j) {
+	if (j.is_null()) {
+		std::cerr << "MSC warning: encountered null ReceivedBy\n";
+		h.emplace_or_replace<Message::Components::ReceivedBy>();
+		return true;
+	}
+
+	if (!j.is_array()) {
+		throw (nlohmann::detail::type_error::create(302, nlohmann::detail::concat("type must be array, but is ", j.type_name()), &j));
+	}
+
+	auto& comp = h.emplace_or_replace<Message::Components::ReceivedBy>();
+
+	if (j.empty()) {
+		// empty comp
+		return true;
+	}
+
+	for (const auto& p : j) {
+		if (!p.is_array()) {
+			throw (nlohmann::detail::type_error::create(302, nlohmann::detail::concat("type must be array, but is ", p.type_name()), &j));
+		}
+
+		comp.ts.emplace(
+			msc.deserlContactByID(p.at(0)), // TODO: error checking?
+			p.at(1).get<decltype(comp.ts)::mapped_type>()
+		);
+	}
 
 	// TODO: should we return false if the contact is unknown??
 	return true;
diff --git a/src/solanaceae/message3/message_serializer.hpp b/src/solanaceae/message3/message_serializer.hpp
index a3024e1..b9b80ac 100644
--- a/src/solanaceae/message3/message_serializer.hpp
+++ b/src/solanaceae/message3/message_serializer.hpp
@@ -70,12 +70,19 @@ struct MessageSerializerNJ {
 	}
 
 	// TODO: deregister
+
+
+
+	// helper
+	nlohmann::json serlContactByID(Contact3 c) const;
+	Contact3 deserlContactByID(const nlohmann::json& j);
 };
 
 // fwd
 namespace Message::Components {
 struct ContactFrom;
 struct ContactTo;
+struct ReceivedBy;
 }
 
 // make specializations known
@@ -87,3 +94,7 @@ template<>
 bool MessageSerializerNJ::component_get_json<Message::Components::ContactTo>(MessageSerializerNJ& msc, const Handle h, nlohmann::json& j);
 template<>
 bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components::ContactTo>(MessageSerializerNJ& msc, Handle h, const nlohmann::json& j);
+template<>
+bool MessageSerializerNJ::component_get_json<Message::Components::ReceivedBy>(MessageSerializerNJ& msc, const Handle h, nlohmann::json& j);
+template<>
+bool MessageSerializerNJ::component_emplace_or_replace_json<Message::Components::ReceivedBy>(MessageSerializerNJ& msc, Handle h, const nlohmann::json& j);
diff --git a/src/solanaceae/message3/nj/message_components.hpp b/src/solanaceae/message3/nj/message_components.hpp
index 451adfe..a9db939 100644
--- a/src/solanaceae/message3/nj/message_components.hpp
+++ b/src/solanaceae/message3/nj/message_components.hpp
@@ -11,12 +11,12 @@ namespace Message::Components {
 	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(Timestamp, ts)
 	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(TimestampProcessed, ts)
 	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(TimestampWritten, ts)
-	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ContactFrom, c)
-	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ContactTo, c)
+	//NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ContactFrom, c) // ms special
+	//NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ContactTo, c) // ms special
 	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(Read, ts)
 
 
-	NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ReceivedBy, ts)
+	//NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ReceivedBy, ts) // ms special
 	// ReadBy
 	// SyncedBy