diff --git a/SignalServiceKit/Messages/Edit/OutgoingEditMessage.swift b/SignalServiceKit/Messages/Edit/OutgoingEditMessage.swift
index 6c683a63d7..b9678b282a 100644
--- a/SignalServiceKit/Messages/Edit/OutgoingEditMessage.swift
+++ b/SignalServiceKit/Messages/Edit/OutgoingEditMessage.swift
@@ -123,23 +123,21 @@ public final class OutgoingEditMessage: TransientOutgoingMessage {
         )
     }
 
-    override public func buildTranscriptSyncMessage(
+    override public func buildSyncTranscriptMessage(
         localThread: TSContactThread,
-        transaction: DBWriteTransaction,
-    ) -> OutgoingSyncMessage? {
-        guard let thread = thread(tx: transaction) else {
-            owsFailDebug("Missing thread for interaction.")
-            return nil
+        tx: DBWriteTransaction,
+    ) throws -> OutgoingSyncMessage {
+        guard let thread = thread(tx: tx) else {
+            throw OWSAssertionError("missing thread for interaction")
         }
 
-        let transcript = OutgoingEditMessageSyncTranscript(
+        return OutgoingEditMessageSyncTranscript(
             localThread: localThread,
             messageThread: thread,
             message: self,
             isRecipientUpdate: false,
-            tx: transaction,
+            tx: tx,
         )
-        return transcript
     }
 
     /// This override is required to properly update the correct interaction row
diff --git a/SignalServiceKit/Messages/Interactions/OutgoingStaticMessage.swift b/SignalServiceKit/Messages/Interactions/OutgoingStaticMessage.swift
index 21be7bdeb7..38804c049c 100644
--- a/SignalServiceKit/Messages/Interactions/OutgoingStaticMessage.swift
+++ b/SignalServiceKit/Messages/Interactions/OutgoingStaticMessage.swift
@@ -61,7 +61,7 @@ final class OutgoingStaticMessage: TransientOutgoingMessage {
 
     override func shouldSyncTranscript() -> Bool { false }
 
-    override func buildPlainTextData(_ thread: TSThread, transaction: DBWriteTransaction) -> Data? {
+    override func buildPlaintextData(inThread thread: TSThread, tx: DBWriteTransaction) throws -> Data {
         return self.plaintextData
     }
 }
diff --git a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.h b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.h
index 93d4fa9929..24b1532ab3 100644
--- a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.h
+++ b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.h
@@ -196,7 +196,9 @@ NS_DESIGNATED_INITIALIZER NS_SWIFT_NAME(init(grdbId:uniqueId:receivedAtTimestamp
 /**
  * The data representation of this message, to be encrypted, before being sent.
  */
-- (nullable NSData *)buildPlainTextData:(TSThread *)thread transaction:(DBWriteTransaction *)transaction;
+- (nullable NSData *)buildPlaintextDataInThread:(TSThread *)thread
+                                             tx:(DBWriteTransaction *)transaction
+                                          error:(NSError **)error NS_SWIFT_NAME(buildPlaintextData(inThread:tx:));
 
 /**
  * Intermediate protobuf representation
@@ -222,9 +224,10 @@ NS_DESIGNATED_INITIALIZER NS_SWIFT_NAME(init(grdbId:uniqueId:receivedAtTimestamp
  */
 - (BOOL)shouldSyncTranscript;
 
-- (nullable OWSOutgoingSyncMessage *)buildTranscriptSyncMessageWithLocalThread:(TSContactThread *)localThread
+- (nullable OWSOutgoingSyncMessage *)buildSyncTranscriptMessageWithLocalThread:(TSContactThread *)localThread
                                                                    transaction:(DBWriteTransaction *)transaction
-    NS_SWIFT_NAME(buildTranscriptSyncMessage(localThread:transaction:));
+                                                                         error:(NSError **)error
+    NS_SWIFT_NAME(buildSyncTranscriptMessage(localThread:tx:));
 
 #pragma mark - Update With... Methods
 
diff --git a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.m b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.m
index 9c815f1b0d..e0fd9cf464 100644
--- a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.m
+++ b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.m
@@ -546,23 +546,11 @@ NSUInteger const TSOutgoingMessageSchemaVersion = 1;
     return contentBuilder;
 }
 
-- (nullable NSData *)buildPlainTextData:(TSThread *)thread transaction:(DBWriteTransaction *)transaction
+- (nullable NSData *)buildPlaintextDataInThread:(TSThread *)thread
+                                             tx:(DBWriteTransaction *)transaction
+                                          error:(NSError **)error
 {
-    SSKProtoContentBuilder *_Nullable contentBuilder = [self contentBuilderWithThread:thread transaction:transaction];
-    if (!contentBuilder) {
-        OWSFailDebug(@"could not build protobuf.");
-        return nil;
-    }
-
-    [contentBuilder setPniSignatureMessage:[self buildPniSignatureMessageIfNeededWithTransaction:transaction]];
-
-    NSError *error;
-    NSData *_Nullable contentData = [contentBuilder buildSerializedDataAndReturnError:&error];
-    if (error || !contentData) {
-        OWSFailDebug(@"could not serialize protobuf: %@", error);
-        return nil;
-    }
-    return contentData;
+    return [self _buildPlaintextDataInThread:thread tx:transaction error:error];
 }
 
 - (BOOL)shouldSyncTranscript
@@ -570,10 +558,11 @@ NSUInteger const TSOutgoingMessageSchemaVersion = 1;
     return YES;
 }
 
-- (nullable OWSOutgoingSyncMessage *)buildTranscriptSyncMessageWithLocalThread:(TSContactThread *)localThread
+- (nullable OWSOutgoingSyncMessage *)buildSyncTranscriptMessageWithLocalThread:(TSContactThread *)localThread
                                                                    transaction:(DBWriteTransaction *)transaction
+                                                                         error:(NSError **)error
 {
-    return [self _buildTranscriptSyncMessageWithLocalThread:localThread tx:transaction];
+    return [self _buildSyncTranscriptMessageWithLocalThread:localThread tx:transaction error:error];
 }
 
 @end
diff --git a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.swift b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.swift
index a1f90dfde7..d90b8762cf 100644
--- a/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.swift
+++ b/SignalServiceKit/Messages/Interactions/TSOutgoingMessage.swift
@@ -371,6 +371,17 @@ extension TSOutgoingMessage {
     @objc
     public var isStorySend: Bool { isGroupStoryReply }
 
+    @objc
+    func _buildPlaintextData(inThread thread: TSThread, tx: DBWriteTransaction) throws -> Data {
+        guard let contentBuilder = self.contentBuilder(thread: thread, transaction: tx) else {
+            throw OWSAssertionError("couldn't build protobuf")
+        }
+        if let pniSignatureMessage = self.buildPniSignatureMessageIfNeeded(tx: tx) {
+            contentBuilder.setPniSignatureMessage(pniSignatureMessage)
+        }
+        return try contentBuilder.buildSerializedData()
+    }
+
     @objc
     func _dataMessageBuilder(thread: TSThread, tx: DBReadTransaction) -> SSKProtoDataMessageBuilder? {
         let builder = SSKProtoDataMessage.builder()
@@ -535,11 +546,11 @@ extension TSOutgoingMessage {
     }
 
     @objc
-    func _buildTranscriptSyncMessage(localThread: TSContactThread, tx: DBWriteTransaction) -> OutgoingSyncMessage? {
+    func _buildSyncTranscriptMessage(localThread: TSContactThread, tx: DBWriteTransaction) throws -> OutgoingSyncMessage {
         owsAssertDebug(self.shouldSyncTranscript())
 
         guard let messageThread = self.thread(tx: tx) else {
-            return nil
+            throw OWSAssertionError("missing thread for sent message")
         }
 
         return OutgoingSentMessageTranscript(
@@ -551,8 +562,7 @@ extension TSOutgoingMessage {
         )
     }
 
-    @objc(buildPniSignatureMessageIfNeededWithTransaction:)
-    func buildPniSignatureMessageIfNeeded(transaction tx: DBReadTransaction) -> SSKProtoPniSignatureMessage? {
+    private func buildPniSignatureMessageIfNeeded(tx: DBReadTransaction) -> SSKProtoPniSignatureMessage? {
         guard recipientAddressStates?.count == 1 else {
             // This is probably a group message, nothing to be alarmed about.
             return nil
diff --git a/SignalServiceKit/Messages/MessageSender.swift b/SignalServiceKit/Messages/MessageSender.swift
index 6c8cab3603..f3890471a1 100644
--- a/SignalServiceKit/Messages/MessageSender.swift
+++ b/SignalServiceKit/Messages/MessageSender.swift
@@ -9,18 +9,8 @@ import LibSignalClient
 // MARK: - Message "isXYZ" properties
 
 extension TSOutgoingMessage {
-    var isTransientSKDM: Bool {
-        (self as? OutgoingSenderKeyDistributionMessage)?.isSentOnBehalfOfOnlineMessage ?? false
-    }
-
-    var isResendRequest: Bool {
-        self is OutgoingResendRequest
-    }
-
-    var isSyncMessage: Bool { self is OutgoingSyncMessage }
-
     var canSendToLocalAddress: Bool {
-        return isSyncMessage ||
+        return self is OutgoingSyncMessage ||
             self is OutgoingCallMessage ||
             self is OutgoingResendRequest ||
             self is OWSOutgoingResendResponse
@@ -471,7 +461,7 @@ public class MessageSender {
         localIdentifiers: LocalIdentifiers,
         tx: DBReadTransaction,
     ) throws -> [SignalServiceAddress] {
-        if message.isSyncMessage {
+        if message is OutgoingSyncMessage {
             return [localIdentifiers.aciAddress]
         }
 
@@ -1149,7 +1139,7 @@ public class MessageSender {
         // transcript is sent.
         //
         // NOTE: This only applies to the 'note to self' conversation.
-        if message.isSyncMessage {
+        if message is OutgoingSyncMessage {
             return
         }
         let thread = SSKEnvironment.shared.databaseStorageRef.read { tx in message.thread(tx: tx) }
@@ -1203,9 +1193,7 @@ public class MessageSender {
         let messageSend = try await databaseStorage.awaitableWrite { tx in
             let localThread = TSContactThread.getOrCreateThread(withContactAddress: localIdentifiers.aciAddress, transaction: tx)
 
-            guard let transcript = message.buildTranscriptSyncMessage(localThread: localThread, transaction: tx) else {
-                throw OWSAssertionError("Failed to build transcript")
-            }
+            let transcript = try message.buildSyncTranscriptMessage(localThread: localThread, tx: tx)
 
             let serializedMessage = try buildAndRecordMessage(transcript, in: localThread, tx: tx)
 
@@ -1233,9 +1221,7 @@ public class MessageSender {
         in thread: TSThread,
         tx: DBWriteTransaction,
     ) throws -> SerializedMessage {
-        guard let plaintextData = message.buildPlainTextData(thread, transaction: tx) else {
-            throw OWSAssertionError("couldn't serialize message")
-        }
+        let plaintextData = try message.buildPlaintextData(inThread: thread, tx: tx)
         let messageSendLog = SSKEnvironment.shared.messageSendLogRef
         let payloadId = messageSendLog.recordPayload(plaintextData, for: message, tx: tx)
         return SerializedMessage(plaintextData: plaintextData, payloadId: payloadId)
@@ -1376,15 +1362,12 @@ public class MessageSender {
         messageSend: OWSMessageSend,
         sealedSenderParameters: SealedSenderParameters?,
     ) async throws -> [DeviceMessage] {
-        guard messageSend.message.encryptionStyle == .whisper || messageSend.message.isResendRequest else {
-            throw OWSAssertionError("Unexpected message type")
-        }
         return try await buildDeviceMessages(
             serviceId: messageSend.serviceId,
             isSelfSend: messageSend.isSelfSend,
             encryptionStyle: messageSend.message.encryptionStyle,
             buildPlaintextContent: { _, _ in messageSend.plaintextContent },
-            isTransient: messageSend.message.isOnline || messageSend.message.isTransientSKDM,
+            isTransient: messageSend.message.isOnline || (messageSend.message as? OutgoingSenderKeyDistributionMessage)?.isSentOnBehalfOfOnlineMessage == true,
             sealedSenderParameters: sealedSenderParameters,
         )
     }
diff --git a/SignalServiceKit/Messages/OWSMessageSend.swift b/SignalServiceKit/Messages/OWSMessageSend.swift
index b1e878a2b8..bdfd75c02c 100644
--- a/SignalServiceKit/Messages/OWSMessageSend.swift
+++ b/SignalServiceKit/Messages/OWSMessageSend.swift
@@ -28,7 +28,7 @@ final class SealedSenderParameters {
         self.endorsement = endorsement
     }
 
-    /// Indicates desired behavior on the case of decryption error.
+    /// Indicates desired behavior if decryption fails.
     var contentHint: SealedSenderContentHint {
         return message.contentHint
     }
diff --git a/SignalServiceKit/Messages/OWSOutgoingResendResponse.swift b/SignalServiceKit/Messages/OWSOutgoingResendResponse.swift
index 64a9fc0e39..1df6684949 100644
--- a/SignalServiceKit/Messages/OWSOutgoingResendResponse.swift
+++ b/SignalServiceKit/Messages/OWSOutgoingResendResponse.swift
@@ -148,7 +148,7 @@ final class OWSOutgoingResendResponse: TransientOutgoingMessage {
 
     override func envelopeGroupIdWithTransaction(_ transaction: DBReadTransaction) -> Data? { self.originalGroupId }
 
-    override func buildPlainTextData(_ thread: TSThread, transaction tx: DBWriteTransaction) -> Data? {
+    override func buildPlaintextData(inThread thread: TSThread, tx: DBWriteTransaction) throws -> Data {
         owsAssertDebug(self.recipientAddresses().count == 1)
 
         let contentBuilder: SSKProtoContentBuilder = {
@@ -188,12 +188,7 @@ final class OWSOutgoingResendResponse: TransientOutgoingMessage {
             }
         }
 
-        do {
-            return try contentBuilder.buildSerializedData()
-        } catch {
-            owsFailDebug("Failed to build plaintext message: \(error)")
-            return nil
-        }
+        return try contentBuilder.buildSerializedData()
     }
 
     private func resentProtoBuilder(from plaintextData: Data) throws -> SSKProtoContentBuilder {
diff --git a/SignalServiceKit/Messages/OutgoingResendRequest.swift b/SignalServiceKit/Messages/OutgoingResendRequest.swift
index 7c7cd0ed85..352d6e587f 100644
--- a/SignalServiceKit/Messages/OutgoingResendRequest.swift
+++ b/SignalServiceKit/Messages/OutgoingResendRequest.swift
@@ -92,14 +92,9 @@ final class OutgoingResendRequest: TransientOutgoingMessage {
         return self.failedEnvelopeGroupId
     }
 
-    override func buildPlainTextData(_ thread: TSThread, transaction: DBWriteTransaction) -> Data? {
-        do {
-            let decryptionErrorMessage = try DecryptionErrorMessage(bytes: decryptionErrorData)
-            let plaintextContent = PlaintextContent(decryptionErrorMessage)
-            return plaintextContent.serialize()
-        } catch {
-            owsFailDebug("Failed to build plaintext: \(error)")
-            return nil
-        }
+    override func buildPlaintextData(inThread thread: TSThread, tx: DBWriteTransaction) throws -> Data {
+        let decryptionErrorMessage = try DecryptionErrorMessage(bytes: decryptionErrorData)
+        let plaintextContent = PlaintextContent(decryptionErrorMessage)
+        return plaintextContent.serialize()
     }
 }
diff --git a/SignalServiceKit/Messages/SendableMessage.swift b/SignalServiceKit/Messages/SendableMessage.swift
index 2702a9fe42..e1334dd043 100644
--- a/SignalServiceKit/Messages/SendableMessage.swift
+++ b/SignalServiceKit/Messages/SendableMessage.swift
@@ -15,26 +15,32 @@ protocol SendableMessage {
 
     var timestamp: UInt64 { get }
 
-    var isSyncMessage: Bool { get }
-
+    /// If true, this message corresponds to a story and should use story=true
+    /// authentication and story account existence semantics.
     var isStorySend: Bool { get }
 
+    /// If true, this message should set the "online" flag to indicate that it
+    /// should only be delivered if the recipient is currently online (e.g.,
+    /// typing indicator messages).
     var isOnline: Bool { get }
 
-    var isTransientSKDM: Bool { get }
-
+    /// If true, this message should set the "urgent" flag (e.g., text messages
+    /// are urgent and receipts are not).
     var isUrgent: Bool { get }
 
-    var isResendRequest: Bool { get }
-
     var canSendToLocalAddress: Bool { get }
 
+    /// Indicates desired behavior if decryption fails.
     var contentHint: SealedSenderContentHint { get }
 
+    /// Indicates how the message should be encrypted.
     var encryptionStyle: EncryptionStyle { get }
 
-    func buildPlainTextData(_ thread: TSThread, transaction: DBWriteTransaction) -> Data?
+    // TODO: Remove the thread parameter?
+    /// Builds the serialized Content protobuf for this message.
+    func buildPlaintextData(inThread thread: TSThread, tx: DBWriteTransaction) throws -> Data
 
+    // TODO: Merge this into the return value when sending a message.
     var wasSentToAnyRecipient: Bool { get }
 
     func recipientAddresses() -> [SignalServiceAddress]
@@ -57,12 +63,23 @@ protocol SendableMessage {
 
     func update(withViewedRecipient recipientAddress: SignalServiceAddress, deviceId: DeviceId, viewedTimestamp timestamp: UInt64, tx: DBWriteTransaction)
 
+    // TODO: Add SyncTranscriptableMessage protocol for these properties.
+
+    /// Indicates that this message needs a sync transcript.
+    ///
+    /// If true, `buildSyncTranscriptMessage` will be invoked.
     func shouldSyncTranscript() -> Bool
 
+    /// Builds a sync transcript for this message.
+    ///
+    /// Only invoked if `shouldSyncTranscript` returns true.
+    func buildSyncTranscriptMessage(localThread: TSContactThread, tx: DBWriteTransaction) throws -> OutgoingSyncMessage
+
     func thread(tx: DBReadTransaction) -> TSThread?
 
     var shouldBeSaved: Bool { get }
 
+    /// True if this message should be stored in the Message Send Log.
     var shouldRecordSendLog: Bool { get }
 
     var relatedUniqueIds: Set<String> { get }
@@ -73,11 +90,6 @@ protocol SendableMessage {
 
     var isViewOnceMessage: Bool { get }
 
-    func buildTranscriptSyncMessage(
-        localThread: TSContactThread,
-        transaction: DBWriteTransaction,
-    ) -> OutgoingSyncMessage?
-
     func update(withHasSyncedTranscript: Bool, transaction: DBWriteTransaction)
 
     func allAttachments(transaction: DBReadTransaction) -> [ReferencedAttachment]
diff --git a/SignalServiceKit/Messages/Stories/OutgoingStoryMessage.swift b/SignalServiceKit/Messages/Stories/OutgoingStoryMessage.swift
index b3e98a8a0a..717a4e983b 100644
--- a/SignalServiceKit/Messages/Stories/OutgoingStoryMessage.swift
+++ b/SignalServiceKit/Messages/Stories/OutgoingStoryMessage.swift
@@ -125,19 +125,18 @@ public class OutgoingStoryMessage: TransientOutgoingMessage {
 
     override public func shouldSyncTranscript() -> Bool { !skipSyncTranscript }
 
-    override public func buildTranscriptSyncMessage(
+    override public func buildSyncTranscriptMessage(
         localThread: TSContactThread,
-        transaction: DBWriteTransaction,
-    ) -> OutgoingSyncMessage? {
-        guard let storyMessage = StoryMessage.anyFetch(uniqueId: storyMessageId, transaction: transaction) else {
-            owsFailDebug("Missing story message")
-            return nil
+        tx: DBWriteTransaction,
+    ) throws -> OutgoingSyncMessage {
+        guard let storyMessage = StoryMessage.anyFetch(uniqueId: storyMessageId, transaction: tx) else {
+            throw OWSAssertionError("missing story message")
         }
 
         return OutgoingStorySentMessageTranscript(
             localThread: localThread,
             storyMessage: storyMessage,
-            transaction: transaction,
+            transaction: tx,
         )
     }
 
diff --git a/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.swift b/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.swift
index 8690b6459c..4ca6933d0f 100644
--- a/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.swift
+++ b/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.swift
@@ -93,7 +93,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = 100
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
             let content = try! SSKProtoContent(serializedData: messageData)
             XCTAssertNil(content.pniSignatureMessage)
         }
@@ -110,7 +110,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = 100
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
             let content = try! SSKProtoContent(serializedData: messageData)
 
             let messagePni = content.pniSignatureMessage!.pni
@@ -136,7 +136,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = Date.ows_millisecondTimestamp()
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
 
             message.updateWithSentRecipients([otherAci], wasSentByUD: true, transaction: transaction)
 
@@ -176,7 +176,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = Date.ows_millisecondTimestamp()
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
 
             message.updateWithSentRecipients([otherAci], wasSentByUD: true, transaction: transaction)
 
@@ -235,7 +235,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = Date.ows_millisecondTimestamp()
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
 
             message.updateWithSentRecipients([otherAci], wasSentByUD: false, transaction: transaction)
 
@@ -275,7 +275,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = Date.ows_millisecondTimestamp()
             let message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
 
             message.updateWithSentRecipients([otherAci], wasSentByUD: true, transaction: transaction)
 
@@ -319,7 +319,7 @@ class TSOutgoingMessageTest: SSKBaseTest {
             messageBuilder.timestamp = Date.ows_millisecondTimestamp()
             message = messageBuilder.build(transaction: transaction)
             message.anyInsert(transaction: transaction)
-            let messageData = message.buildPlainTextData(thread, transaction: transaction)!
+            let messageData = try! message.buildPlaintextData(inThread: thread, tx: transaction)
 
             message.updateWithSentRecipients([otherAci], wasSentByUD: true, transaction: transaction)