fix: correct email batch api call with reply_to

src/batch/batch.ts

@@ -1,4 +1,6 @@
 import type * as React from 'react';
+import type { EmailApiOptions } from '../common/interfaces/email-api-options.interface';
+import { parseEmailToApiOptions } from '../common/utils/parse-email-to-api-options';
 import type { Resend } from '../resend';
 import type {
   CreateBatchOptions,
@@ -22,6 +24,8 @@ export class Batch {
     payload: CreateBatchOptions,
     options: CreateBatchRequestOptions = {},
   ): Promise<CreateBatchResponse> {
+    const emails: EmailApiOptions[] = [];
+
     for (const email of payload) {
       if (email.react) {
         if (!this.renderAsync) {
@@ -38,11 +42,13 @@ export class Batch {
         email.html = await this.renderAsync(email.react as React.ReactElement);
         email.react = undefined;
       }
+
+      emails.push(parseEmailToApiOptions(email));
     }
 
     const data = await this.resend.post<CreateBatchSuccessResponse>(
       '/emails/batch',
-      payload,
+      emails,
       options,
     );
 

src/common/interfaces/email-api-options.interface.ts

@@ -0,0 +1,18 @@
+import type { Attachment } from '../../emails/interfaces/create-email-options.interface';
+import type { Tag } from '../../interfaces';
+
+export interface EmailApiOptions {
+  from: string;
+  to: string | string[];
+  subject: string;
+  region?: string;
+  headers?: Record<string, string>;
+  html?: string;
+  text?: string;
+  bcc?: string | string[];
+  cc?: string | string[];
+  reply_to?: string | string[];
+  scheduled_at?: string;
+  tags?: Tag[];
+  attachments?: Attachment[];
+}

src/common/utils/parse-email-to-api-options.spec.ts

@@ -0,0 +1,44 @@
+import type { CreateEmailOptions } from '../../emails/interfaces/create-email-options.interface';
+import { parseEmailToApiOptions } from './parse-email-to-api-options';
+
+describe('parseEmailToApiOptions', () => {
+  it('should handle minimal email with only required fields', () => {
+    const emailPayload: CreateEmailOptions = {
+      from: 'joao@resend.com',
+      to: 'bu@resend.com',
+      subject: 'Hey, there!',
+      html: '<h1>Hey, there!</h1>',
+    };
+
+    const apiOptions = parseEmailToApiOptions(emailPayload);
+
+    expect(apiOptions).toEqual({
+      from: 'joao@resend.com',
+      to: 'bu@resend.com',
+      subject: 'Hey, there!',
+      html: '<h1>Hey, there!</h1>',
+    });
+  });
+
+  it('should properly parse camel case to snake case', () => {
+    const emailPayload: CreateEmailOptions = {
+      from: 'joao@resend.com',
+      to: 'bu@resend.com',
+      subject: 'Hey, there!',
+      html: '<h1>Hey, there!</h1>',
+      replyTo: 'zeno@resend.com',
+      scheduledAt: 'in 1 min',
+    };
+
+    const apiOptions = parseEmailToApiOptions(emailPayload);
+
+    expect(apiOptions).toEqual({
+      from: 'joao@resend.com',
+      to: 'bu@resend.com',
+      subject: 'Hey, there!',
+      html: '<h1>Hey, there!</h1>',
+      reply_to: 'zeno@resend.com',
+      scheduled_at: 'in 1 min',
+    });
+  });
+});

src/common/utils/parse-email-to-api-options.ts

@@ -0,0 +1,21 @@
+import type { CreateEmailOptions } from '../../emails/interfaces/create-email-options.interface';
+import type { EmailApiOptions } from '../interfaces/email-api-options.interface';
+
+export function parseEmailToApiOptions(
+  email: CreateEmailOptions,
+): EmailApiOptions {
+  return {
+    attachments: email.attachments,
+    bcc: email.bcc,
+    cc: email.cc,
+    from: email.from,
+    headers: email.headers,
+    html: email.html,
+    reply_to: email.replyTo,
+    scheduled_at: email.scheduledAt,
+    subject: email.subject,
+    tags: email.tags,
+    text: email.text,
+    to: email.to,
+  };
+}

src/emails/emails.ts

@@ -1,4 +1,5 @@
 import type * as React from 'react';
+import { parseEmailToApiOptions } from '../common/utils/parse-email-to-api-options';
 import type { Resend } from '../resend';
 import type {
   CancelEmailResponse,
@@ -54,20 +55,7 @@ export class Emails {
 
     const data = await this.resend.post<CreateEmailResponseSuccess>(
       '/emails',
-      {
-        attachments: payload.attachments,
-        bcc: payload.bcc,
-        cc: payload.cc,
-        from: payload.from,
-        headers: payload.headers,
-        html: payload.html,
-        reply_to: payload.replyTo,
-        scheduled_at: payload.scheduledAt,
-        subject: payload.subject,
-        tags: payload.tags,
-        text: payload.text,
-        to: payload.to,
-      },
+      parseEmailToApiOptions(payload),
       options,
     );
 

src/emails/interfaces/create-email-options.interface.ts

@@ -103,7 +103,7 @@ export interface CreateEmailResponse {
   error: ErrorResponse | null;
 }
 
-interface Attachment {
+export interface Attachment {
   /** Content of an attached file. */
   content?: string | Buffer;
   /** Name of attached file. */