Verify an email address in C#

Checking that an address parses is a regex. Checking that it can actually receive mail requires a DNS lookup, a disposable-provider list and a scoring model. This endpoint does all three in one call.

C#

using var http = new HttpClient();
http.DefaultRequestHeaders.Add("Authorization", $"Bearer {apiKey}");
var json = await http.GetStringAsync(
    "https://autorev.rohnelt.dev/v1/email/verify?email=john.doe@gmail.com");
Console.WriteLine(json);

Response

{
  "email": "john.doe@gmail.com",
  "status": "deliverable",
  "score": 87,
  "normalized": "johndoe@gmail.com",
  "has_mx": true,
  "is_disposable": false,
  "is_role": false,
  "did_you_mean": null
}

The three checks that matter

1. MX reachability. A domain with no MX and no A record cannot receive mail at all - that is a hard bounce you can avoid for free.
2. Disposable detection. Blocks trial abuse at signup.
3. Typo correction. gmial.con becomes a "did you mean gmail.com?" prompt instead of a lost customer.