# Build a custom flow for handling email links (Legacy)

> This guide is for users who want to build a custom flow. To use a _prebuilt_ UI, use the [Account Portal pages](https://clerk.com/docs/guides/account-portal/overview.md?sdk=nextjs) or [prebuilt components](https://clerk.com/docs/nextjs/reference/components/overview.md).

> This guide uses the Core 2 `useSignIn()` and `useSignUp()` hooks, which are available in Core 3 SDKs by adding the `/legacy` subpath to the import path. If you're using a Core 2 SDK, remove the `/legacy` subpath.

[Email links](https://clerk.com/docs/guides/configure/auth-strategies/sign-up-sign-in-options.md?sdk=nextjs) can be used to sign up new users, sign in existing users, or allow existing users to verify newly added email addresses to their user profiles.

1. The user enters their email address and asks for an email link.
2. Clerk sends an email to the user, containing a link to the verification URL.
3. The user visits the email link, either on the same device where they entered their email address or on a different device, depending on the settings in the Clerk Dashboard.
4. Clerk verifies the user's identity and advances any sign-up or sign-in attempt that might be in progress.
5. If the verification is successful, the user is authenticated or their email address is verified, depending on the reason for the email link.

This guide demonstrates how to use Clerk's API to build a custom flow for handling email links. It covers the following scenarios:

- [Sign up](https://clerk.com/docs/nextjs/guides/development/custom-flows/authentication/legacy/email-links.md#sign-up-flow)
- [Sign in](https://clerk.com/docs/nextjs/guides/development/custom-flows/authentication/legacy/email-links.md#sign-in-flow)
- [Verify a new email address](https://clerk.com/docs/nextjs/guides/development/custom-flows/authentication/legacy/email-links.md#add-new-email-flow)

## Enable email link authentication

To allow your users to sign up or sign in using email links, you must first configure the appropriate settings in the Clerk Dashboard.

1. In the Clerk Dashboard, navigate to the [**User & authentication**](https://dashboard.clerk.com/~/user-authentication/user-and-authentication) page.
2. Enable **Verify at sign-up**, and under **Verification methods**, enable **Email verification link**.
3. Enable **Sign-in with email**. Because this guide focuses on email links, disable **Email verification code** and enable **Email verification link**. By default, **Require the same device and browser** is enabled, which means that email links are required to be verified from the same device and browser on which the sign-up or sign-in was initiated. For this guide, leave this setting enabled.

## Sign-up flow

1. The [useSignUp()](https://clerk.com/docs/nextjs/reference/hooks/use-sign-up.md) hook is used to get the [SignUp](https://clerk.com/docs/nextjs/reference/objects/sign-up.md) object.
2. The `SignUp` object is used to access the [createEmailLinkFlow()](https://clerk.com/docs/nextjs/reference/types/email-address.md#create-email-link-flow) method.
3. The `createEmailLinkFlow()` method is used to access the `startEmailLinkFlow()` method.
4. The `startEmailLinkFlow()` method is called with the `redirectUrl` parameter set to `/sign-up/verify`. It sends an email with a verification link to the user. When the user visits the link, they are redirected to the URL that was provided.
5. On the `/sign-up/verify` page, the [useClerk()](https://clerk.com/docs/nextjs/reference/hooks/use-clerk.md) hook is used to get the [handleEmailLinkVerification()](https://clerk.com/docs/nextjs/reference/objects/clerk.md#handle-email-link-verification) method.
6. The `handleEmailLinkVerification()` method is called to verify the email address. Error handling is included to handle any errors that occur during the verification process.

**Sign up page**

filename: app/sign-up/[[...sign-up]]/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useSignUp } from '@clerk/nextjs/legacy'

export default function SignInPage() {
  const [emailAddress, setEmailAddress] = React.useState('')
  const [verified, setVerified] = React.useState(false)
  const [verifying, setVerifying] = React.useState(false)
  const [error, setError] = React.useState('')
  const { signUp, isLoaded } = useSignUp()

  if (!isLoaded) return null

  const { startEmailLinkFlow } = signUp.createEmailLinkFlow()

  async function submit(e: React.FormEvent) {
    e.preventDefault()
    // Reset states in case user resubmits form mid sign-up
    setVerified(false)
    setError('')

    setVerifying(true)

    if (!isLoaded && !signUp) return null

    // Start the sign-up process using the email provided
    try {
      await signUp.create({
        emailAddress,
      })

      // Dynamically set the host domain for dev and prod
      // You could instead use an environment variable or other source for the host domain
      const protocol = window.location.protocol
      const host = window.location.host

      // Send the user an email with the email link
      const signUpAttempt = await startEmailLinkFlow({
        // URL to navigate to after the user visits the link in their email
        redirectUrl: `${protocol}//${host}/sign-up/verify`,
      })

      // Check the verification result
      const verification = signUpAttempt.verifications.emailAddress

      // Handle if user visited the link and completed sign-up from /sign-up/verify
      if (verification.verifiedFromTheSameClient()) {
        setVerifying(false)
        setVerified(true)
      }
    } catch (err: any) {
      // See https://clerk.com/docs/guides/development/custom-flows/error-handling
      // for more info on error handling
      console.error(JSON.stringify(err, null, 2))

      if (err.errors?.[0]?.longMessage) {
        console.log('Clerk error:', err.errors[0].longMessage)
        setError(err.errors[0].longMessage)
      } else {
        setError('An error occurred.')
      }
    }
  }

  async function reset(e: React.FormEvent) {
    e.preventDefault()
    setVerifying(false)
  }

  if (error) {
    return (
      <div>
        <p>Error: {error}</p>
        <button onClick={() => setError('')}>Try again</button>
      </div>
    )
  }

  if (verifying) {
    return (
      <div>
        <p>Check your email and visit the link that was sent to you.</p>
        <form onSubmit={reset}>
          <button type="submit">Restart</button>
        </form>
      </div>
    )
  }

  if (verified) {
    return <div>Signed up successfully!</div>
  }

  return (
    <div>
      <h1>Sign up</h1>
      <form onSubmit={submit}>
        <input
          type="email"
          placeholder="Enter email address"
          value={emailAddress}
          onChange={(e) => setEmailAddress(e.target.value)}
        />
        <button type="submit">Continue</button>
      </form>
    </div>
  )
}
```

**Verify page**

filename: app/sign-up/verify/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useClerk } from '@clerk/nextjs/legacy'
import { EmailLinkErrorCodeStatus, isEmailLinkError } from '@clerk/nextjs/errors'
import Link from 'next/link'

export default function VerifyEmailLink() {
  const [verificationStatus, setVerificationStatus] = React.useState('loading')

  const { handleEmailLinkVerification, loaded } = useClerk()

  async function verify() {
    try {
      // Dynamically set the host domain for dev and prod
      // You could instead use an environment variable or other source for the host domain
      const protocol = window.location.protocol
      const host = window.location.host

      await handleEmailLinkVerification({
        // URL to navigate to if sign-up flow needs more requirements, such as MFA
        redirectUrl: `${protocol}//${host}/sign-up`,
      })

      // If not redirected at this point,
      // the flow has completed
      setVerificationStatus('verified')
    } catch (err: any) {
      let status = 'failed'

      if (isEmailLinkError(err)) {
        // If link expired, set status to expired
        if (err.code === EmailLinkErrorCodeStatus.Expired) {
          status = 'expired'
        } else if (err.code === EmailLinkErrorCodeStatus.ClientMismatch) {
          // OPTIONAL: This check is only required if you have
          // the 'Require the same device and browser' setting
          // enabled in the Clerk Dashboard
          status = 'client_mismatch'
        }
      }

      setVerificationStatus(status)
    }
  }

  React.useEffect(() => {
    if (!loaded) return

    verify()
  }, [handleEmailLinkVerification, loaded])

  if (verificationStatus === 'loading') {
    return <div>Loading...</div>
  }

  if (verificationStatus === 'failed') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link verification failed.</p>
        <Link href="/sign-up">Sign up</Link>
      </div>
    )
  }

  if (verificationStatus === 'expired') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link has expired.</p>
        <Link href="/sign-up">Sign up</Link>
      </div>
    )
  }

  // OPTIONAL: This check is only required if you have
  // the 'Require the same device and browser' setting
  // enabled in the Clerk Dashboard
  if (verificationStatus === 'client_mismatch') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>
          You must complete the email link sign-up on the same device and browser that you started
          it on.
        </p>
        <Link href="/sign-up">Sign up</Link>
      </div>
    )
  }

  return (
    <div>
      <h1>Verify your email</h1>
      <p>Successfully signed up. Return to the original tab to continue.</p>
    </div>
  )
}
```

## Sign-in flow

1. The [useSignIn()](https://clerk.com/docs/nextjs/reference/hooks/use-sign-in.md) hook is used to get the [SignIn](https://clerk.com/docs/nextjs/reference/objects/sign-in.md) object.
2. The `SignIn` object is used to access the [createEmailLinkFlow()](https://clerk.com/docs/nextjs/reference/types/email-address.md#create-email-link-flow) method.
3. The `createEmailLinkFlow()` method is used to access the `startEmailLinkFlow()` method.
4. The `startEmailLinkFlow()` method is called with the `redirectUrl` parameter set to `/sign-in/verify`. It sends an email with a verification link to the user. When the user visits the link, they are redirected to the URL that was provided.
5. On the `/sign-in/verify` page, the [useClerk()](https://clerk.com/docs/nextjs/reference/hooks/use-clerk.md) hook is used to get the [handleEmailLinkVerification()](https://clerk.com/docs/nextjs/reference/objects/clerk.md#handle-email-link-verification) method.
6. The `handleEmailLinkVerification()` method is called to verify the email address. Error handling is included to handle any errors that occur during the verification process.

**Sign in page**

filename: app/sign-in/[[...sign-in]]/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useSignIn } from '@clerk/nextjs/legacy'
import { EmailLinkFactor, SignInFirstFactor } from '@clerk/shared/types'

export default function SignInPage() {
  const [emailAddress, setEmailAddress] = React.useState('')
  const [verified, setVerified] = React.useState(false)
  const [verifying, setVerifying] = React.useState(false)
  const [error, setError] = React.useState('')
  const { signIn, isLoaded } = useSignIn()

  if (!isLoaded) return null

  const { startEmailLinkFlow } = signIn.createEmailLinkFlow()

  async function submit(e: React.FormEvent) {
    e.preventDefault()
    // Reset states in case user resubmits form mid sign-in
    setVerified(false)
    setError('')

    if (!isLoaded && !signIn) return null

    // Start the sign-in process using the email provided
    try {
      const { supportedFirstFactors } = await signIn.create({
        identifier: emailAddress,
      })

      setVerifying(true)

      // Filter the returned array to find the 'email_link' entry
      const isEmailLinkFactor = (factor: SignInFirstFactor): factor is EmailLinkFactor => {
        return factor.strategy === 'email_link'
      }
      const emailLinkFactor = supportedFirstFactors?.find(isEmailLinkFactor)

      if (!emailLinkFactor) {
        setError('Email link factor not found')
        return
      }

      const { emailAddressId } = emailLinkFactor

      // Dynamically set the host domain for dev and prod
      // You could instead use an environment variable or other source for the host domain
      const protocol = window.location.protocol
      const host = window.location.host

      // Send the user an email with the email link
      const signInAttempt = await startEmailLinkFlow({
        emailAddressId,
        redirectUrl: `${protocol}//${host}/sign-in/verify`,
      })

      // Check the verification result
      const verification = signInAttempt.firstFactorVerification

      // Handle if verification expired
      if (verification.status === 'expired') {
        setError('The email link has expired.')
      }

      // Handle if user visited the link and completed sign-in from /sign-in/verify
      if (verification.verifiedFromTheSameClient()) {
        setVerifying(false)
        setVerified(true)
      }
    } catch (err: any) {
      // See https://clerk.com/docs/guides/development/custom-flows/error-handling
      // for more info on error handling
      console.error(JSON.stringify(err, null, 2))
      setError('An error occurred.')
    }
  }

  async function reset(e: React.FormEvent) {
    e.preventDefault()
    setVerifying(false)
  }

  if (error) {
    return (
      <div>
        <p>Error: {error}</p>
        <button onClick={() => setError('')}>Try again</button>
      </div>
    )
  }

  if (verifying) {
    return (
      <div>
        <p>Check your email and visit the link that was sent to you.</p>
        <form onSubmit={reset}>
          <button type="submit">Restart</button>
        </form>
      </div>
    )
  }

  if (verified) {
    return <div>Signed in successfully!</div>
  }

  return (
    <div>
      <h1>Sign in</h1>
      <form onSubmit={submit}>
        <input
          type="email"
          placeholder="Enter email address"
          value={emailAddress}
          onChange={(e) => setEmailAddress(e.target.value)}
        />
        <button type="submit">Continue</button>
      </form>
    </div>
  )
}
```

**Verify page**

filename: app/sign-in/verify/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useClerk } from '@clerk/nextjs/legacy'
import { EmailLinkErrorCodeStatus, isEmailLinkError } from '@clerk/nextjs/errors'
import Link from 'next/link'

export default function VerifyEmailLink() {
  const [verificationStatus, setVerificationStatus] = React.useState('loading')

  const { handleEmailLinkVerification, loaded } = useClerk()

  async function verify() {
    try {
      // Dynamically set the host domain for dev and prod
      // You could instead use an environment variable or other source for the host domain
      const protocol = window.location.protocol
      const host = window.location.host

      await handleEmailLinkVerification({
        // URL to navigate to if sign-in flow needs more requirements, such as MFA
        redirectUrl: `${protocol}//${host}/sign-in`,
      })

      // If not redirected at this point,
      // the flow has completed
      setVerificationStatus('verified')
    } catch (err: any) {
      let status = 'failed'

      if (isEmailLinkError(err)) {
        // If link expired, set status to expired
        if (err.code === EmailLinkErrorCodeStatus.Expired) {
          status = 'expired'
        } else if (err.code === EmailLinkErrorCodeStatus.ClientMismatch) {
          // OPTIONAL: This check is only required if you have
          // the 'Require the same device and browser' setting
          // enabled in the Clerk Dashboard
          status = 'client_mismatch'
        }
      }

      setVerificationStatus(status)
      return
    }
  }

  React.useEffect(() => {
    if (!loaded) return

    verify()
  }, [handleEmailLinkVerification, loaded])

  if (verificationStatus === 'loading') {
    return <div>Loading...</div>
  }

  if (verificationStatus === 'failed') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link verification failed.</p>
        <Link href="/sign-in">Sign in</Link>
      </div>
    )
  }

  if (verificationStatus === 'expired') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link has expired.</p>
        <Link href="/sign-in">Sign in</Link>
      </div>
    )
  }

  // OPTIONAL: This check is only required if you have
  // the 'Require the same device and browser' setting
  // enabled in the Clerk Dashboard
  if (verificationStatus === 'client_mismatch') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>
          You must complete the email link sign-in on the same device and browser as you started it
          on.
        </p>
        <Link href="/sign-in">Sign in</Link>
      </div>
    )
  }

  return (
    <div>
      <h1>Verify your email</h1>
      <p>Successfully signed in. Return to the original tab to continue.</p>
    </div>
  )
}
```

## Add new email flow

When a user adds an email address to their account, you can use email links to verify the email address.

1. Every user has a [User](https://clerk.com/docs/nextjs/reference/objects/user.md) object that represents their account. The `User` object has a `emailAddresses` property that contains all the email addresses associated with the user. Use the [useUser()](https://clerk.com/docs/nextjs/reference/hooks/use-user.md) hook to access the `User` object.
2. Pass the [User.createEmailAddress()](https://clerk.com/docs/nextjs/reference/objects/user.md#create-email-address) method to the [useReverification()](https://clerk.com/docs/nextjs/reference/hooks/use-reverification.md) hook to require the user to [reverify their credentials](https://clerk.com/docs/guides/secure/reverification.md?sdk=nextjs) before being able to add an email address to their account.
3. If the `createEmailAddress()` function is successful, a new [EmailAddress](https://clerk.com/docs/nextjs/reference/types/email-address.md) object is created and stored in `User.emailAddresses`. Use the newly created `EmailAddress` object to access the [createEmailLinkFlow()](https://clerk.com/docs/nextjs/reference/types/email-address.md#create-email-link-flow) method.
4. Use the `createEmailLinkFlow()` method to access the [startEmailLinkFlow()](https://clerk.com/docs/nextjs/reference/types/email-address.md#create-email-link-flow) method. Call the `startEmailLinkFlow()` method to send an email with a verification link to the user. This method requires specifying a `redirectUrl`, which is the URL that the user will be redirected to after visiting the link in their email.
5. On your verification page (the URL you set as the `redirectUrl` parameter), call the [useClerk()](https://clerk.com/docs/nextjs/reference/hooks/use-clerk.md) hook to access the [handleEmailLinkVerification()](https://clerk.com/docs/nextjs/reference/objects/clerk.md#handle-email-link-verification) method.
6. Call the `handleEmailLinkVerification()` method to verify the email address.

**Add email page**

filename: app/account/add-email/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useUser, useReverification } from '@clerk/nextjs'

export default function Page() {
  const { isLoaded, isSignedIn, user } = useUser()
  const createEmailAddress = useReverification((email: string) =>
    user?.createEmailAddress({ email }),
  )

  const [email, setEmail] = React.useState('')
  const [verifying, setVerifying] = React.useState(false)
  const [error, setError] = React.useState('')

  // Handle loading state
  if (!isLoaded) <p>Loading...</p>

  // Handle signed-out state
  if (!isSignedIn) <p>You must be signed in to access this page</p>

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault()

    try {
      setVerifying(true)

      // Add an unverified email address to user
      const res = await createEmailAddress(email)
      // Reload user to get updated User object
      await user?.reload()

      // Find the email address that was just added
      const emailAddress = user?.emailAddresses.find((a) => a.id === res?.id)

      if (!emailAddress) {
        setError('Email address not found')
        return
      }

      const { startEmailLinkFlow } = emailAddress.createEmailLinkFlow()

      // Dynamically set the host domain for dev and prod
      // You could instead use an environment variable or other source for the host domain
      const protocol = window.location.protocol
      const host = window.location.host

      // Send the user an email with the verification link
      startEmailLinkFlow({ redirectUrl: `${protocol}//${host}/account/add-email/verify` })
    } catch (err) {
      // See https://clerk.com/docs/guides/development/custom-flows/error-handling
      // for more info on error handling
      console.error(JSON.stringify(err, null, 2))
      setError('An error occurred.')
    }
  }

  async function reset(e: React.FormEvent) {
    e.preventDefault()
    setVerifying(false)
  }

  if (error) {
    return (
      <div>
        <p>Error: {error}</p>
        <button onClick={() => setError('')}>Try again</button>
      </div>
    )
  }

  if (verifying) {
    return (
      <div>
        <p>Check your email and visit the link that was sent to you.</p>
        <form onSubmit={reset}>
          <button type="submit">Restart</button>
        </form>
      </div>
    )
  }

  // Display the initial form to capture the email address
  return (
    <>
      <h1>Add email</h1>
      <div>
        <form onSubmit={(e) => handleSubmit(e)}>
          <label htmlFor="email">Enter email address</label>
          <input
            id="email"
            name="email"
            type="email"
            value={email}
            onChange={(e) => setEmail(e.target.value)}
          />
          <button type="submit">Continue</button>
        </form>
      </div>
    </>
  )
}
```

**Verify page**

filename: app/account/add-email/verify/page.tsx
```tsx
'use client'

import * as React from 'react'
import { useClerk } from '@clerk/nextjs'
import { EmailLinkErrorCodeStatus, isEmailLinkError } from '@clerk/nextjs/errors'
import Link from 'next/link'

export type VerificationStatus =
  | 'expired'
  | 'failed'
  | 'loading'
  | 'verified'
  | 'verified_switch_tab'
  | 'client_mismatch'

export default function VerifyEmailLink() {
  const [verificationStatus, setVerificationStatus] = React.useState('loading')

  const { handleEmailLinkVerification, loaded } = useClerk()

  async function verify() {
    try {
      await handleEmailLinkVerification({})
      setVerificationStatus('verified')
    } catch (err: any) {
      let status: VerificationStatus = 'failed'

      if (isEmailLinkError(err)) {
        // If link expired, set status to expired
        if (err.code === EmailLinkErrorCodeStatus.Expired) {
          status = 'expired'
        } else if (err.code === EmailLinkErrorCodeStatus.ClientMismatch) {
          // OPTIONAL: This check is only required if you have
          // the 'Require the same device and browser' setting
          // enabled in the Clerk Dashboard
          status = 'client_mismatch'
        }
      }

      setVerificationStatus(status)
      return
    }
  }

  React.useEffect(() => {
    if (!loaded) return

    verify()
  }, [handleEmailLinkVerification, loaded])

  if (verificationStatus === 'loading') {
    return <div>Loading...</div>
  }

  if (verificationStatus === 'failed') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link verification failed.</p>
        <Link href="/account/add-email">Return to add email</Link>
      </div>
    )
  }

  if (verificationStatus === 'expired') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>The email link has expired.</p>
        <Link href="/account/add-email">Return to add email</Link>
      </div>
    )
  }

  // OPTIONAL: This check is only required if you have
  // the 'Require the same device and browser' setting
  // enabled in the Clerk Dashboard
  if (verificationStatus === 'client_mismatch') {
    return (
      <div>
        <h1>Verify your email</h1>
        <p>
          You must complete the email link verification on the same device and browser as you
          started it on.
        </p>
        <Link href="/account/add-email">Return to add email</Link>
      </div>
    )
  }

  return (
    <div>
      <h1>Verify your email</h1>
      <p>Successfully added email!</p>
    </div>
  )
}
```

---

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