# Address verification

An add-on that stops mail to addresses that don't exist before it is sent, so your bounce rate stays low and those sends never count toward your plan.

## What is checked

Every email a project with the add-on sends is checked against Rasket's address book first: every address we have delivered to, received authenticated mail from, or seen bounce. An address we already know is answered at once and is free.

An address we haven't seen before gets, in order:

- free checks: its spelling, its domain's mail servers, and known disposable and role addresses;
- a mailbox check: we ask the address's own mail server whether the mailbox exists, from servers that never send mail, and never send a message.

Only the mailbox check is billed, once per address. Each answer is remembered, so the same address is never checked again.

## What each verdict does

| Verdict | Means | When you send |
| --- | --- | --- |
| Valid | The mailbox exists. | Sent. |
| Invalid | The mail server said the mailbox doesn't exist. | Not sent. |
| Risky | A role address such as info@ or sales@, a disposable domain, or a domain that accepts every address. | Sent with Send anyway; not sent with Don't send. |
| Unknown | The mail server wouldn't say, or we couldn't ask it. | Sent. |

You choose what a risky address does in Settings → Add-ons: **Send anyway** (the default) or **Don't send**. Don't send also refuses role addresses, which B2B mail often goes to.

A send to an address we don't know waits at most 1.5 seconds for its mailbox check, then goes out. Campaigns are checked ahead of sending.

## When an address is refused

A refused address is not sent to and never counts as one of your plan's emails. It fires `email.suppressed` with reason `failed_verification`. A single send whose every recipient is refused answers `422`, with `details.cause` `failed_verification` — [see Errors](https://www.rasket.com/docs/errors).

## Verify a list

On a segment's page or an import's page, **Verify list** checks every contact on it in the background. Before it starts you see how many addresses we already know (free), how many may need a mailbox check, and the most it can cost.

When it is done the page shows how many are valid, invalid, risky and unknown, with two buttons: **Remove invalid** deletes those contacts from your audience, and **Tag risky** adds the risky ones to a segment named Risky addresses. The same is in the API as `POST /contacts/verifications`.

> Imports made before the add-on shipped can't be verified by import: verify a segment that holds them instead.

## Price

$2 per 1,000 mailbox checks, on your next invoice. Addresses we already know and the free checks cost nothing. On a Shopify bill, checks are charged per started 1,000. It is available on every paid plan, and you can turn it off at any time.