Edge Functions

Custom Auth Emails with React Email and Resend


Use the send email hook to send custom auth emails with React Email and Resend in Supabase Edge Functions.

Prerequisites

To get the most out of this guide, you’ll need to:

Make sure you have the latest version of the Supabase CLI installed.

1. Create Supabase function

Create a new function locally:

1
supabase functions new send-email

2. Edit the handler function

Paste the following code into the index.ts file:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
import React from 'npm:react@18.3.1'import { Webhook } from 'https://esm.sh/standardwebhooks@1.0.0'import { Resend } from 'npm:resend@4.0.0'import { renderAsync } from 'npm:@react-email/components@0.0.22'import { MagicLinkEmail } from './_templates/magic-link.tsx'const resend = new Resend(Deno.env.get('RESEND_API_KEY') as string)const hookSecret = Deno.env.get('SEND_EMAIL_HOOK_SECRET') as stringDeno.serve(async (req) => { if (req.method !== 'POST') { return new Response('not allowed', { status: 400 }) } const payload = await req.text() const headers = Object.fromEntries(req.headers) const wh = new Webhook(hookSecret) try { const { user, email_data: { token, token_hash, redirect_to, email_action_type }, } = wh.verify(payload, headers) as { user: { email: string } email_data: { token: string token_hash: string redirect_to: string email_action_type: string site_url: string token_new: string token_hash_new: string } } const html = await renderAsync( React.createElement(MagicLinkEmail, { supabase_url: Deno.env.get('SUPABASE_URL') ?? '', token, token_hash, redirect_to, email_action_type, }) ) const { error } = await resend.emails.send({ from: 'welcome <onboarding@resend.dev>', to: [user.email], subject: 'Supa Custom MagicLink!', html, }) if (error) { throw error } } catch (error) { console.log(error) return new Response( JSON.stringify({ error: { http_code: error.code, message: error.message, }, }), { status: 401, headers: { 'Content-Type': 'application/json' }, } ) } const responseHeaders = new Headers() responseHeaders.set('Content-Type', 'application/json') return new Response(JSON.stringify({}), { status: 200, headers: responseHeaders, })})

3. Create React Email templates

Create a new folder _templates and create a new file magic-link.tsx with the following code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
import { Body, Container, Head, Heading, Html, Link, Preview, Text,} from 'npm:@react-email/components@0.0.22'import * as React from 'npm:react@18.3.1'interface MagicLinkEmailProps { supabase_url: string email_action_type: string redirect_to: string token_hash: string token: string}export const MagicLinkEmail = ({ token, supabase_url, email_action_type, redirect_to, token_hash,}: MagicLinkEmailProps) => ( <Html> <Head /> <Preview>Log in with this magic link</Preview> <Body style={main}> <Container style={container}> <Heading style={h1}>Login</Heading> <Link href={`${supabase_url}/auth/v1/verify?token=${token_hash}&type=${email_action_type}&redirect_to=${redirect_to}`} target="_blank" style={{ ...link, display: 'block', marginBottom: '16px', }} > Click here to log in with this magic link </Link> <Text style={{ ...text, marginBottom: '14px' }}> Or, copy and paste this temporary login code: </Text> <code style={code}>{token}</code> <Text style={{ ...text, color: '#ababab', marginTop: '14px', marginBottom: '16px', }} > If you didn&apos;t try to login, you can safely ignore this email. </Text> <Text style={footer}> <Link href="https://demo.vercel.store/" target="_blank" style={{ ...link, color: '#898989' }} > ACME Corp </Link> , the famouse demo corp. </Text> </Container> </Body> </Html>)export default MagicLinkEmailconst main = { backgroundColor: '#ffffff',}const container = { paddingLeft: '12px', paddingRight: '12px', margin: '0 auto',}const h1 = { color: '#333', fontFamily: "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif", fontSize: '24px', fontWeight: 'bold', margin: '40px 0', padding: '0',}const link = { color: '#2754C5', fontFamily: "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif", fontSize: '14px', textDecoration: 'underline',}const text = { color: '#333', fontFamily: "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif", fontSize: '14px', margin: '24px 0',}const footer = { color: '#898989', fontFamily: "-apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif", fontSize: '12px', lineHeight: '22px', marginTop: '12px', marginBottom: '24px',}const code = { display: 'inline-block', padding: '16px 4.5%', width: '90.5%', backgroundColor: '#f4f4f4', borderRadius: '5px', border: '1px solid #eee', color: '#333',}

4. Deploy the Function

Deploy function to Supabase:

1
supabase functions deploy send-email --no-verify-jwt

Note down the function URL, you will need it in the next step!

5. Configure the Send Email Hook

  • Go to the Auth Hooks section of the Supabase dashboard and create a new "Send Email hook".
  • Select HTTPS as the hook type.
  • Paste the function URL in the "URL" field.
  • Click "Generate Secret" to generate your webhook secret and note it down.
  • Click "Create" to save the hook configuration.

Store these secrets in your .env file.

1
2
RESEND_API_KEY=your_resend_api_keySEND_EMAIL_HOOK_SECRET=<base64_secret>

Set the secrets from the .env file:

1
supabase secrets set --env-file supabase/functions/.env

Now your Supabase Edge Function will be triggered anytime an Auth Email needs to be send to the user!

More resources