> ## Documentation Index > Fetch the complete documentation index at: https://docs.autosend.com/llms.txt > Use this file to discover all available pages before exploring further. # Send emails with Better Auth > Learn how to send authentication emails using AutoSend with Better Auth for email verification, password reset, and OTP. export const APP_PATHS = { home: '/', quickstart: '/quickstart', domainConfiguration: '/domain', apiReference: '/api-reference', sendEmail: '/api-reference/mails/send', bulkSendEmail: '/api-reference/mails/bulk', upsertContactApiRef: '/api-reference/contacts/upsert-contact', transactional: '/transactional-emails', emailActivity: '/transactional-emails/email-activity', emailTemplates: '/transactional-emails/email-templates', sendingEmail: '/quickstart/email-using-api', transactionalTroubleshooting: '/transactional-emails/troubleshooting', marketing: '/marketing-emails', campaigns: '/marketing-emails/campaigns', contacts: '/marketing-emails/contacts', contactsIntroduction: '/marketing-emails/contacts/introduction', contactsImportCsv: '/marketing-emails/contacts/import-csv', contactsLists: '/marketing-emails/contacts/lists', contactsSegments: '/marketing-emails/contacts/segments', contactsCustomFields: '/marketing-emails/contacts/contact-properties', contactsContactProperties: '/marketing-emails/contacts/contact-properties', createContactPropertyApiRef: '/api-reference/contact-properties/create', listContactPropertiesApiRef: '/api-reference/contact-properties/list', getContactPropertyApiRef: '/api-reference/contact-properties/get-by-name', deleteContactPropertyApiRef: '/api-reference/contact-properties/delete', sender: '/marketing-emails/sender', unsubscribeGroups: '/others/unsubscribe-groups', webhookIntroduction: '/others/webhooks/introduction', webhookEventType: '/others/webhooks/event-type', webhookRetries: '/others/webhooks/retries', webhookVerifyRequests: '/others/webhooks/verify-requests', dynamicTemplates: '/dynamic-templates', guides: '/guides', sitemap: '/sitemap.xml', team: '/others/team', automations: '/automations', events: '/automations/events', sendEventApi: '/api-reference/events/send-event', smtpIntroduction: '/quickstart/smtp', betterAuth: '/guides/better-auth', convexGuide: '/guides/convex', templateVariables: '/transactional-emails/variables', suppressions: '/others/suppressions', rateLimit: '/api-reference/rate-limit', nodejsSdk: '/sdk/nodejs', smtpIntegrationGuides: '/guides/smtp', apiKeys: '/api-keys', encryptedPayloads: '/others/encrypted-payloads', apiReferenceIntroduction: '/api-reference/introduction', lovableGuide: '/ai/integrations/lovable', aiIntroduction: '/ai/introduction', aiSkills: '/ai/skills', aiMcpServer: '/ai/mcp-server', aiLovable: '/ai/integrations/lovable', aiBolt: '/ai/integrations/bolt', aiV0: '/ai/integrations/v0', aiReplit: '/ai/integrations/replit', mcpClaude: '/ai/mcp-clients/claude', mcpCursor: '/ai/mcp-clients/cursor', mcpCopilot: '/ai/mcp-clients/copilot', mcpWindsurf: '/ai/mcp-clients/windsurf', mcpCodex: '/ai/mcp-clients/codex', mcpAntigravity: '/ai/mcp-clients/antigravity', mcpChatgpt: '/ai/mcp-clients/chatgpt', mcpRaycast: '/ai/mcp-clients/raycast', domainWarmup: '/marketing-emails/domain-warmup', projects: '/projects', createAutomationApi: '/api-reference/automations/create-automation', migrationSendgrid: '/migration/sendgrid', migrationResend: '/migration/resend', auth0CustomAction: '/guides/auth0-custom-action', accountBilling: '/others/account/billing', accountUsage: '/others/account/usage', inboundIntroduction: '/inbound/introduction', listInboundMessagesApi: '/api-reference/inbound-emails/list-messages', getInboundMessageApi: '/api-reference/inbound-emails/get-message', downloadInboundAttachmentApi: '/api-reference/inbound-emails/download-attachment', replyToInboundMessageApi: '/api-reference/inbound-emails/reply-to-message', wikiDailySendingLimit: '/wiki/daily-sending-limit' }; AutoSend x Better Auth This guide shows you how to integrate AutoSend with [Better Auth](https://www.better-auth.com) to send authentication emails. Better Auth is a framework-agnostic authentication library for TypeScript that supports email verification, password reset, and OTP-based authentication. ## Prerequisites Make sure you have a verified domain added in AutoSend to send emails from. Create a new API key for SMTP authentication or use the existing one. ## Installation Install Better Auth in your project if you haven't already: ```bash theme={null} npm install better-auth ``` ## Integration Add the required environment variables to your `.env` file: ```bash .env theme={null} AUTOSEND_API_KEY=your_autosend_api_key_here FROM_EMAIL=noreply@yourdomain.com FROM_NAME=Your App Name ``` Get your API key from the [API Keys](https://autosend.com/settings/api-key) page in your AutoSend dashboard. Create a helper function to send emails via the AutoSend API using templates: ```typescript lib/autosend.ts theme={null} const AUTOSEND_API_KEY = process.env.AUTOSEND_API_KEY!; const FROM_EMAIL = process.env.FROM_EMAIL || "noreply@yourdomain.com"; const FROM_NAME = process.env.FROM_NAME || "Your App"; interface SendEmailOptions { to: string; templateId: string; dynamicData: Record; } export async function sendEmail({ to, templateId, dynamicData }: SendEmailOptions) { const response = await fetch("https://api.autosend.com/v1/mails/send", { method: "POST", headers: { Authorization: `Bearer ${AUTOSEND_API_KEY}`, "Content-Type": "application/json", }, body: JSON.stringify({ from: { email: FROM_EMAIL, name: FROM_NAME, }, to: { email: to, }, templateId, dynamicData, }), }); if (!response.ok) { const error = await response.json(); throw new Error(error.message || "Failed to send email"); } return response.json(); } ``` Create email templates in your [AutoSend dashboard](https://app.autosend.com) for each authentication flow: | Template | Suggested ID | Variables | | ------------------ | --------------------- | ------------------------------------- | | Email verification | `tmpl_verify_email` | `{{userName}}`, `{{verificationUrl}}` | | Password reset | `tmpl_password_reset` | `{{userName}}`, `{{resetUrl}}` | | Sign-in OTP | `tmpl_otp_signin` | `{{otp}}` | | Verification OTP | `tmpl_otp_verify` | `{{otp}}` | | Password reset OTP | `tmpl_otp_reset` | `{{otp}}` | Learn more about template variables. Wire up your Better Auth configuration to send emails through AutoSend: ```typescript lib/auth.ts theme={null} import { betterAuth } from "better-auth"; import { emailOTP } from "better-auth/plugins"; import { sendEmail } from "./autosend"; export const auth = betterAuth({ // ... your database and other configuration emailVerification: { sendOnSignUp: true, sendVerificationEmail: async ({ user, url }) => { sendEmail({ to: user.email, templateId: "tmpl_verify_email", dynamicData: { userName: user.name || "there", verificationUrl: url, }, }); }, }, emailAndPassword: { enabled: true, sendResetPassword: async ({ user, url }) => { sendEmail({ to: user.email, templateId: "tmpl_password_reset", dynamicData: { userName: user.name || "there", resetUrl: url, }, }); }, }, plugins: [ emailOTP({ sendVerificationOTP: async ({ email, otp, type }) => { const templateIds = { "sign-in": "tmpl_otp_signin", "email-verification": "tmpl_otp_verify", "forget-password": "tmpl_otp_reset", }; sendEmail({ to: email, templateId: templateIds[type], dynamicData: { otp }, }); }, }), ], }); ``` Don't await email sending to prevent timing attacks. This ensures response time doesn't reveal whether an email was sent. For client-side setup (sending OTPs, verifying codes), see the [Better Auth Email OTP documentation](https://www.better-auth.com/docs/plugins/email-otp). ## Serverless Considerations When running on serverless platforms (Vercel, AWS Lambda, Cloudflare Workers), ensure email sending completes before the function terminates. Use `waitUntil` to ensure the email is sent: ```typescript theme={null} import { waitUntil } from '@vercel/functions'; import { sendEmail } from './autosend'; // In your Better Auth config sendVerificationEmail: async ({ user, url }) => { waitUntil( sendEmail({ to: user.email, templateId: 'tmpl_verify_email', dynamicData: { userName: user.name || 'there', verificationUrl: url, }, }) ); }; ``` Use the `ctx.waitUntil` method: ```typescript theme={null} sendVerificationEmail: async ({ user, url }) => { // Access ExecutionContext from your request handler ctx.waitUntil( sendEmail({ to: user.email, templateId: 'tmpl_verify_email', dynamicData: { userName: user.name || 'there', verificationUrl: url, }, }) ); }; ``` ## Troubleshooting If you receive a "Domain not verified" error, ensure your sending domain is properly configured in AutoSend. **Solution:** Go to your [Domain Settings](https://autosend.com/settings/domains) and complete the DNS verification process. A 401 error indicates your API key is invalid or missing. **Solution:** 1. Check your `.env` file has the correct `AUTOSEND_API_KEY` 2. Verify the key in your [API Keys](https://autosend.com/settings/api-key) dashboard 3. Ensure the key hasn't been revoked If you're sending too many emails, you may hit rate limits. **Solution:** Review the Rate Limits documentation and implement appropriate throttling in your application. If emails aren't being delivered: 1. Check the [Email Activity](https://autosend.com/email-activities) dashboard for delivery status 2. Verify the recipient email is valid 3. Check if the email is in [Suppressions](https://autosend.com/suppressions/global) 4. Review the Troubleshooting Guide for common issues ## Next Steps Create reusable, personalized email templates for transactional emails. Use webhooks to notify your application about email and contact events in real-time. Here's a step-by-step guide on how to verify and authenticate domain on AutoSend for sending emails. Track delivery, performance, and troubleshoot issues for your transactional emails.