# boolean_smtp_pro_upgrade_url

> Filters the URL shown to users to upgrade to BooleanSMTP Pro.

Filter · Tier B · Since 1.0.0



## Signature

```php
add_filter( 'boolean_smtp_pro_upgrade_url', $callback, 10, 1 );
```

## Parameters

| Name | Type | Description |
| --- | --- | --- |
| `$url` | `string` | The default upgrade URL. Return a different URL to redirect upgrade prompts elsewhere. |

**Returns** `string` — The filtered URL.

## Fires in

- [app/Support/NullProCapability.php:111](https://github.com/booleanpress/boolean-smtp-src/blob/main/app/Support/NullProCapability.php#L111) — `BooleanSmtp\Support\NullProCapability::getUpgradeUrl()`
- [boolean-smtp-pro/app/Services/ProCapabilityService.php:58](https://github.com/booleanpress/boolean-smtp-src/blob/main/boolean-smtp-pro/app/Services/ProCapabilityService.php#L58) — `BooleanSmtpPro\Services\ProCapabilityService::getUpgradeUrl()`

## Example

```php
add_filter( 'boolean_smtp_pro_upgrade_url', function ( string $url ) {
    return $url;
}, 10, 1 );
```