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SvelteKit email validation reference

Arcjet allows you validate & verify an email address. This is useful for preventing users from signing up with fake email addresses and can significantly reduce the amount of spam or fraudulent accounts.

Configuration

Email validation is configured by specifying the email types you wish to block and whether you wish to modify certain validation options.

The configuration definition is:

type EmailOptions = {
  mode?: "LIVE" | "DRY_RUN";
  block?: ArcjetEmailType[];
  requireTopLevelDomain?: boolean; // default: true
  allowDomainLiteral?: boolean; // default: false
};

The arcjet client is configured with one or many validateEmail rules which take EmailOptions.

Which email types to block is configured by listing the types in the configuration block.

The validation options can usually be left as the defaults. However, if you wish to allow certain types of email addresses, you can modify the options:

  • requireTopLevelDomain: Whether or not to allow email addresses that don’t contain at least 2 domain segments (the domain name and TLD). Defaults to true. Changing to false means that foo@bar would be allowed.
  • allowDomainLiteral: Whether or not to allow email addresses with domain literals. Defaults to false. Changing to true means that foo@[123.456.789.0] would be allowed.

Decision

Arcjet provides a single protect function that is used to execute your protection rules. This requires a RequestEvent property which is the event context as passed to the request handler. When configured with a validateEmail rule it also requires an additional email prop.

This function returns a Promise that resolves to an ArcjetDecision object. This contains the following properties:

  • id (string) - The unique ID for the request. This can be used to look up the request in the Arcjet dashboard. It is prefixed with req_ for decisions involving the Arcjet cloud API. For decisions taken locally, the prefix is lreq_.
  • conclusion (ArcjetConclusion) - The final conclusion based on evaluating each of the configured rules. If you wish to accept Arcjet’s recommended action based on the configured rules then you can use this property.
  • reason (ArcjetReason) - An object containing more detailed information about the conclusion.
  • results (ArcjetRuleResult[]) - An array of ArcjetRuleResult objects containing the results of each rule that was executed.
  • ip (ArcjetIpDetails) - An object containing Arcjet’s analysis of the client IP address. See IP analysis in the SDK reference for more information.

See the SDK reference for more details about the rule results.

You check if a deny conclusion has been returned by an email validation rule by using decision.isDenied() and decision.reason.isEmail().

You can iterate through the results and check whether an email validation rule was applied:

for (const result of decision.results) {
  console.log("Rule Result", result);
}

This example will log the full result as well as the email validation rule:

/src/routes/api/arcjet/+server.ts
import { env } from "$env/dynamic/private";
import arcjet, { detectBot, validateEmail } from "@arcjet/sveltekit";
import { error, json, type RequestEvent } from "@sveltejs/kit";


const aj = arcjet({
  key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com
  rules: [
    validateEmail({
      mode: "LIVE",
      block: ["DISPOSABLE"],
    }),
    detectBot({
      mode: "LIVE",
      allow: [], // "allow none" will block all detected bots
    }),
  ],
});


export async function POST(event: RequestEvent) {
  const decision = await aj.protect(event, {
    // The email prop is required when a validateEmail rule is configured.
    // TypeScript will guide you based on the configured rules
    email: "test@0zc7eznv3rsiswlohu.tk",
  });


  for (const result of decision.results) {
    console.log("Rule Result", result);


    if (result.reason.isEmail()) {
      console.log("Email rule", result);
    }
  }


  if (decision.isDenied()) {
    return error(403, "Forbidden");
  }


  return json({ message: "Hello world" });
}

Checking the email type

Arcjet will return the type of email address that was verified. This will be one or several of the reported email types.

// See https://docs.arcjet.com/email-validation/concepts#email-types
type ArcjetEmailType =
  | "DISPOSABLE" // Disposable email address from a throwaway email service
  | "FREE" // Email address from a free email service
  | "NO_MX_RECORDS" // Email address with no MX records i.e. is undeliverable
  | "NO_GRAVATAR" // Email address with no Gravatar profile
  | "INVALID"; // Email address that is invalid

Error handling

Arcjet is designed to fail open so that a service issue or misconfiguration does not block all requests. The SDK will also time out and fail open after 1000ms when NODE_ENV or ARCJET_ENV is development and 500ms otherwise. However, in most cases, the response time will be less than 20-30ms.

If there is an error condition, Arcjet will return an ERROR conclusion.

/src/routes/api/arcjet/+server.ts
import { env } from "$env/dynamic/private";
import arcjet, { validateEmail } from "@arcjet/sveltekit";
import { error, json, type RequestEvent } from "@sveltejs/kit";


const aj = arcjet({
  key: env.ARCJET_KEY!, // Get your site key from https://app.arcjet.com
  rules: [
    validateEmail({
      mode: "LIVE",
      block: ["DISPOSABLE"],
    }),
  ],
});


export async function POST(event: RequestEvent) {
  const decision = await aj.protect(event, {
    // The email prop is required when a validateEmail rule is configured.
    // TypeScript will guide you based on the configured rules
    email: "test@0zc7eznv3rsiswlohu.tk",
  });


  if (decision.isErrored()) {
    // Fail open by logging the error and continuing
    console.warn("Arcjet error", decision.reason.message);
    // You could also fail closed here for very sensitive routes
    //return error(503, { message: "Service unavailable" });
  }


  if (decision.isDenied()) {
    return error(403, { message: "Forbidden" });
  }


  return json({ message: "Hello world" });
}

Testing

Arcjet runs the same in any environment, including locally and in CI. You can use the mode set to DRY_RUN to log the results of rule execution without blocking any requests.

We have an example test framework you can use to automatically test your rules. Arcjet can also be triggered based using a sample of your traffic.

See the Testing section of the docs for details.

Discussion