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FAQ
Last update: 10th August 2021.

Reacher API

What is your accuracy rate?

Since we check emails on the spot, in real-time, the accuracy rate is high. Depending on the value of the email's reachability, we guarantee the following accuracies:
  • safe: We guarantee a hard bounce rate lower than 3%. Bounce rates may still happen, because we connect to the email's SMTP server from a different IP address than you, and yours might be blacklisted.
  • invalid: We guarantee with a confidence of 99% that this email is not deliverable.
  • risky: The email address appears to exist, but has quality issues that may result in low engagement or a bounce. We don't recommend sending to these emails, and don't commit on an accuracy rate.
  • unknown: It might happen on rare occasions that the email provider doesn't allow real-time verification of emails. In this case, there's unfortunately nothing Reacher can do. Please let us know if this happens, we're working on finding ways to solve these issues, which in most occasions are solved on a case-by-case basis.

What does is_reachable: "unknown" mean?

It might happen on rare occasions that the email provider doesn't allow real-time verification of emails. In this case, there's unfortunately nothing Reacher can do. Please let us know if this happens, we're working on finding clever ways to work around these issues.

What are hard bounces?

Hard bounces are email addresses that could not be delivered, for example due to an invalid mailbox. They are treated very seriously by most email service providers.

Do you provider bulk email validation?

Reacher currently does not provide bulk email validation as a service.
If you want to validate large volumes of email, please consider purchasing the Commercial License, which allows for self-hosting Reacher's software on your own infrastructure and allows unlimited verifications. See πŸŽ“Reacher Licenses for more info.
We are currently working on an API endpoint which accepts a list of email addresses, as well as list uploads (CSV, XLS). If these features interest you, please let us know by upvoting the feature here: https://github.com/reacherhq/backend/issues/149.

How is real-time verification done?

The process is fairly straightforward and outlined in the telnet script below.
We first form a connection to the mail server with a basic TCP connection on port 25. We then identify ourselves as example.com and a reply-to email of testing@example.com. The last step, and the most important in this process is the RCPT command. This is where, based on the response from the mail server, we are able to conclude the deliverability of a given email address. A 200 implies a valid inbox and anything else implies either an error with our connection to the mail server, or a problem with the address requested. A full outline of all the status codes we parse can be found here.
telnet mail.abccorp.com 25
HELO example.com
MAIL FROM: testing@example.com
RCPT TO: your_email@somedomain.com
If you can read some code, then the best is to check out Reacher's open-source code at https://github.com/reacherhq/check-if-email-exists.

How to use Reacher with a proxy?

Reacher allows verifying emails using a SOCK5 proxy. Please note that HTTP proxies are not supported, because Reacher performs SMTP checks which happen on a different protocol than HTTP.
To verifying an email using a proxy, simply send an API request with a proxy field:
{
	"to_email": "someone@gmail.com",
	"proxy": {
		"host": "{your proxy IP or hostname}",
		"port": {your proxy port}
	}
}
Please also see the πŸ“–REST API Documentation for more details about the endpoint.

Account, Billing & Security

How secure is my data?

Reacher takes security and privacy seriously. It's simple, we do not store the emails you check, and we do not share your data with any third parties. The email verification is done in real-time, and once it's finished, we clear everything.

Is your service GDPR-compliant?

Yes, our service is based in France, so is fully compliant with the GDPR by law. Please refer to our πŸ“—Privacy Policy for more information.

What form of payments do you accept?

Payment can be made by Visa, MasterCard or Amex. Behind the scenes, we use Stripe ConnectΒ to process payments.

Self-Hosting & Commercial License

How many verifications can I do per month?

With the Commercial License plan, the number of verifications is unlimited.

How to debug when self-hosting?

Whether you're using Docker or running the binary from a server, simply set the environment variable to RUST_LOG=debug before running the software. Then, when performing the API request, the full debug logs will show on the server terminal, or in docker logs.
If you want a more robust debug monitoring system, for example to debug "is_reachable": "unknown", we recommend setting up https://sentry.io/ (unaffiliated link). Reacher's backend comes with an optional Sentry plugin, please see 🏠Self-Host Guide for a setup guide.

Who is the team behind Reacher?

I'm Amaury, an indie developer based in Paris πŸ‡«πŸ‡·. Say hi to me πŸ‘‹! βœ‰οΈ amaury@reacher.email.
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