get critical error when changing email option

Hi, when I change the mail function (E-Mail options) from wc_mail() to wp_mail() or mail(), I get the following critical error. Due to spf, I need to use the wp_mail smtp and not the woocommerce system. Any ideas how to fix that?

The error:

Fatal error: Uncaught Error: Class “WC_Email” not found in /xxx/wp-content/plugins/email-verification-for-woocommerce-pro/includes/pro/class-alg-wc-ev-pro.php:688 Stack trace: #0 /xxx/wp-includes/class-wp-hook.php(310): Alg_WC_Email_Verification_Pro->maybe_add_wc_email_style(‘IMPORTANT:\r\n<br…’, ‘wp_mail’) #1 /xxx/wp-includes/plugin.php(205): WP_Hook->apply_filters(‘IMPORTANT:\r\n<br…’, Array) #2 /xxx/wp-content/plugins/email-verification-for-woocommerce-pro/includes/class-alg-wc-ev-emails.php(380): apply_filters(‘alg_wc_ev_send_…’, ‘IMPORTANT:\r\n<br…’, ‘wp_mail’) #3 /xxx/wp-content/plugins/email-verification-for-woocommerce-pro/includes/class-alg-wc-ev-emails.php(306): Alg_WC_Email_Verification_Emails->send_mail(‘xxx@gmail…’, ‘Please activate…’, ‘IMPORTANT:\r\n<br…’) #4 /xxx/wp-content/plugins/email-verification-for-woocommerce-pro/includes/class-alg-wc-ev-core.php(744): Alg_WC_Email_Verification_Emails->reset_and_mail_activation_link(‘264’) #5 /xxx/wp-includes/class-wp-hook.php(310): Alg_WC_Email_Verification_Core->resend(”) #6 /xxx/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters(false, Array) #7 /xxx/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #8 /xxx/wp-settings.php(632): do_action(‘init’) #9 /xxx/wp-config.php(41): require_once(‘/www/htdocs/w01…’) #10 /xxx/wp-load.php(50): require_once(‘/www/htdocs/w01…’) #11 /xxx/wp-blog-header.php(13): require_once(‘/www/htdocs/w01…’) #12 /xxx/index.php(17): require(‘/www/htdocs/w01…’) #13 {main} thrown in /xxx/wp-content/plugins/email-verification-for-woocommerce-pro/includes/pro/class-alg-wc-ev-pro.php on line 688