feat: add In-Reply-To option (#165)

apps/web/package.json

@@ -23,7 +23,7 @@
     "@aws-sdk/client-sns": "^3.797.0",
     "@aws-sdk/s3-request-presigner": "^3.797.0",
     "@hono/swagger-ui": "^0.5.1",
-    "@hono/zod-openapi": "^0.19.5",
+    "@hono/zod-openapi": "^0.10.0",
     "@hookform/resolvers": "^5.0.1",
     "@isaacs/ttlcache": "^1.4.1",
     "@prisma/client": "^6.6.0",

apps/web/prisma/migrations/20250523232535_add_in_reply_to/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "Email" ADD COLUMN     "inReplyToId" TEXT;

apps/web/prisma/schema.prisma

@@ -245,6 +245,7 @@ model Email {
   attachments  String?
   campaignId   String?
   contactId    String?
+  inReplyToId  String?
   team         Team         @relation(fields: [teamId], references: [id], onDelete: Cascade)
   emailEvents  EmailEvent[]
 

apps/web/src/server/aws/ses.ts

@@ -103,96 +103,7 @@ export async function getDomainIdentity(domain: string, region: string) {
   return response;
 }
 
-export async function sendEmailThroughSes({
-  to,
-  from,
-  subject,
-  cc,
-  bcc,
-  text,
-  html,
-  replyTo,
-  region,
-  configurationSetName,
-  unsubUrl,
-  isBulk,
-}: Partial<EmailContent> & {
-  region: string;
-  configurationSetName: string;
-  cc?: string[];
-  bcc?: string[];
-  replyTo?: string[];
-  to?: string[];
-  isBulk?: boolean;
-}) {
-  const sesClient = getSesClient(region);
-  const command = new SendEmailCommand({
-    FromEmailAddress: from,
-    ReplyToAddresses: replyTo ? replyTo : undefined,
-    Destination: {
-      ToAddresses: to,
-      CcAddresses: cc,
-      BccAddresses: bcc,
-    },
-    Content: {
-      // EmailContent
-      Simple: {
-        // Message
-        Subject: {
-          // Content
-          Data: subject, // required
-          Charset: "UTF-8",
-        },
-        Body: {
-          // Body
-          Text: text
-            ? {
-                Data: text, // required
-                Charset: "UTF-8",
-              }
-            : undefined,
-          Html: html
-            ? {
-                Data: html, // required
-                Charset: "UTF-8",
-              }
-            : undefined,
-        },
-        Headers: [
-          // Spread in any unsubscribe headers if unsubUrl is defined
-          ...(unsubUrl
-            ? [
-                { Name: "List-Unsubscribe", Value: `<${unsubUrl}>` },
-                {
-                  Name: "List-Unsubscribe-Post",
-                  Value: "List-Unsubscribe=One-Click",
-                },
-              ]
-            : []),
-          // Spread in the precedence header if present
-          ...(isBulk ? [{ Name: "Precedence", Value: "bulk" }] : []),
-          {
-            Name: "X-Entity-Ref-ID",
-            Value: nanoid(),
-          },
-        ],
-      },
-    },
-    ConfigurationSetName: configurationSetName,
-  });
-
-  try {
-    const response = await sesClient.send(command);
-    console.log("Email sent! Message ID:", response.MessageId);
-    return response.MessageId;
-  } catch (error) {
-    console.error("Failed to send email", error);
-    throw error;
-  }
-}
-
-// Need to improve this. Use some kinda library to do this
-export async function sendEmailWithAttachments({
+export async function sendRawEmail({
   to,
   from,
   subject,
@@ -200,22 +111,28 @@ export async function sendEmailWithAttachments({
   cc,
   bcc,
   // eslint-disable-next-line no-unused-vars
-  text,
+  text, // text is not used directly in raw email but kept for interface consistency
   html,
   attachments,
   region,
   configurationSetName,
+  unsubUrl,
+  isBulk,
+  inReplyToMessageId,
 }: Partial<EmailContent> & {
   region: string;
   configurationSetName: string;
-  attachments: { filename: string; content: string }[];
+  attachments?: { filename: string; content: string }[]; // Made attachments optional
   cc?: string[];
   bcc?: string[];
   replyTo?: string[];
   to?: string[];
+  unsubUrl?: string;
+  isBulk?: boolean;
+  inReplyToMessageId?: string;
 }) {
   const sesClient = getSesClient(region);
-  const boundary = "NextPart";
+  const boundary = `NextPart`;
   let rawEmail = `From: ${from}\n`;
   rawEmail += `To: ${Array.isArray(to) ? to.join(", ") : to}\n`;
   rawEmail += cc && cc.length ? `Cc: ${cc.join(", ")}\n` : "";
@@ -224,19 +141,37 @@ export async function sendEmailWithAttachments({
     replyTo && replyTo.length ? `Reply-To: ${replyTo.join(", ")}\n` : "";
   rawEmail += `Subject: ${subject}\n`;
   rawEmail += `MIME-Version: 1.0\n`;
+
+  // Add headers
+  if (unsubUrl) {
+    rawEmail += `List-Unsubscribe: <${unsubUrl}>\n`;
+    rawEmail += `List-Unsubscribe-Post: List-Unsubscribe=One-Click\n`;
+  }
+  if (isBulk) {
+    rawEmail += `Precedence: bulk\n`;
+  }
+  if (inReplyToMessageId) {
+    rawEmail += `In-Reply-To: <${inReplyToMessageId}@email.amazonses.com>\n`;
+    rawEmail += `References: <${inReplyToMessageId}@email.amazonses.com>\n`;
+  }
+  rawEmail += `X-Entity-Ref-ID: ${nanoid()}\n`;
+
   rawEmail += `Content-Type: multipart/mixed; boundary="${boundary}"\n\n`;
   rawEmail += `--${boundary}\n`;
   rawEmail += `Content-Type: text/html; charset="UTF-8"\n\n`;
   rawEmail += `${html}\n\n`;
-  for (const attachment of attachments) {
-    const content = attachment.content; // Convert buffer to base64
-    const mimeType =
-      mime.lookup(attachment.filename) || "application/octet-stream";
-    rawEmail += `--${boundary}\n`;
-    rawEmail += `Content-Type: ${mimeType}; name="${attachment.filename}"\n`;
-    rawEmail += `Content-Disposition: attachment; filename="${attachment.filename}"\n`;
-    rawEmail += `Content-Transfer-Encoding: base64\n\n`;
-    rawEmail += `${content}\n\n`;
+
+  if (attachments && attachments.length > 0) {
+    for (const attachment of attachments) {
+      const content = attachment.content; // Assumes content is base64
+      const mimeType =
+        mime.lookup(attachment.filename) || "application/octet-stream";
+      rawEmail += `--${boundary}\n`;
+      rawEmail += `Content-Type: ${mimeType}; name="${attachment.filename}"\n`;
+      rawEmail += `Content-Disposition: attachment; filename="${attachment.filename}"\n`;
+      rawEmail += `Content-Transfer-Encoding: base64\n\n`;
+      rawEmail += `${content}\n\n`;
+    }
   }
 
   rawEmail += `--${boundary}--`;
@@ -252,11 +187,13 @@ export async function sendEmailWithAttachments({
 
   try {
     const response = await sesClient.send(command);
-    console.log("Email with attachments sent! Message ID:", response.MessageId);
+    console.log("Email sent! Message ID:", response.MessageId);
     return response.MessageId;
   } catch (error) {
-    console.error("Failed to send email with attachments", error);
-    throw new Error("Failed to send email with attachments");
+    console.error("Failed to send email", error);
+    // It's better to throw the original error or a new error with more context
+    // throw new Error("Failed to send email");
+    throw error;
   }
 }
 

apps/web/src/server/public-api/api/emails/send-email.ts

@@ -1,6 +1,5 @@
 import { createRoute, z } from "@hono/zod-openapi";
 import { PublicAPIApp } from "~/server/public-api/hono";
-import { getTeamFromToken } from "~/server/public-api/auth";
 import { sendEmail } from "~/server/service/email-service";
 import { emailSchema } from "../../schemas/email-schema";
 

apps/web/src/server/public-api/hono.ts

@@ -70,7 +70,6 @@ export function getApp() {
 
     let currentRequests: number;
     let ttl: number;
-    let isNewKey = false;
 
     try {
       // Increment the key. If the key does not exist, it is created and set to 1.

apps/web/src/server/public-api/schemas/email-schema.ts

@@ -29,6 +29,7 @@ export const emailSchema = z
       .max(10) // Limit attachments array size if desired
       .optional(),
     scheduledAt: z.string().datetime({ offset: true }).optional(), // Ensure ISO 8601 format with offset
+    inReplyToId: z.string().optional().nullable(),
   })
   .refine(
     (data) => !!data.subject || !!data.templateId,

apps/web/src/server/service/email-queue-service.ts

@@ -4,7 +4,7 @@ import { EmailAttachment } from "~/types";
 import { convert as htmlToText } from "html-to-text";
 import { getConfigurationSetName } from "~/utils/ses-utils";
 import { db } from "../db";
-import { sendEmailThroughSes, sendEmailWithAttachments } from "../aws/ses";
+import { sendRawEmail } from "../aws/ses";
 import { getRedis } from "../redis";
 import { DEFAULT_QUEUE_OPTIONS } from "../queue/queue-constants";
 import { Prisma } from "@prisma/client";
@@ -331,34 +331,37 @@ async function executeEmail(
       ? htmlToText(email.html)
       : undefined;
 
+  let inReplyToMessageId: string | undefined = undefined;
+
+  if (email.inReplyToId) {
+    const replyEmail = await db.email.findUnique({
+      where: {
+        id: email.inReplyToId,
+      },
+    });
+
+    if (replyEmail && replyEmail.sesEmailId) {
+      inReplyToMessageId = replyEmail.sesEmailId;
+    }
+  }
+
   try {
-    const messageId = attachments.length
-      ? await sendEmailWithAttachments({
-          to: email.to,
-          from: email.from,
-          subject: email.subject,
-          replyTo: email.replyTo ?? undefined,
-          bcc: email.bcc,
-          cc: email.cc,
-          text,
-          html: email.html ?? undefined,
-          region: domain?.region ?? env.AWS_DEFAULT_REGION,
-          configurationSetName,
-          attachments,
-        })
-      : await sendEmailThroughSes({
-          to: email.to,
-          from: email.from,
-          subject: email.subject,
-          replyTo: email.replyTo ?? undefined,
-          text,
-          html: email.html ?? undefined,
-          region: domain?.region ?? env.AWS_DEFAULT_REGION,
-          configurationSetName,
-          attachments,
-          unsubUrl,
-          isBulk,
-        });
+    const messageId = await sendRawEmail({
+      to: email.to,
+      from: email.from,
+      subject: email.subject,
+      replyTo: email.replyTo ?? undefined,
+      bcc: email.bcc,
+      cc: email.cc,
+      text,
+      html: email.html ?? undefined,
+      region: domain?.region ?? env.AWS_DEFAULT_REGION,
+      configurationSetName,
+      attachments: attachments.length > 0 ? attachments : undefined,
+      unsubUrl,
+      isBulk,
+      inReplyToMessageId,
+    });
 
     // Delete attachments after sending the email
     await db.email.update({

apps/web/src/server/service/email-service.ts

@@ -63,6 +63,7 @@ export async function sendEmail(
     bcc,
     scheduledAt,
     apiKeyId,
+    inReplyToId,
   } = emailContent;
   let subject = subjectFromApiCall;
   let html = htmlFromApiCall;
@@ -99,6 +100,22 @@ export async function sendEmail(
     }
   }
 
+  if (inReplyToId) {
+    const email = await db.email.findUnique({
+      where: {
+        id: inReplyToId,
+        teamId,
+      },
+    });
+
+    if (!email) {
+      throw new UnsendApiError({
+        code: "BAD_REQUEST",
+        message: '"inReplyTo" is invalid',
+      });
+    }
+  }
+
   if (!text && !html) {
     throw new UnsendApiError({
       code: "BAD_REQUEST",
@@ -131,6 +148,7 @@ export async function sendEmail(
       scheduledAt: scheduledAtDate,
       latestStatus: scheduledAtDate ? "SCHEDULED" : "QUEUED",
       apiId: apiKeyId,
+      inReplyToId,
     },
   });
 

apps/web/src/types/index.ts

@@ -3,7 +3,7 @@ export type EmailContent = {
   from: string;
   subject?: string;
   templateId?: string;
-  variables?: Record<string, string>,
+  variables?: Record<string, string>;
   text?: string;
   html?: string;
   replyTo?: string | string[];
@@ -12,6 +12,7 @@ export type EmailContent = {
   attachments?: Array<EmailAttachment>;
   unsubUrl?: string;
   scheduledAt?: string;
+  inReplyToId?: string | null;
 };
 
 export type EmailAttachment = {