invoiceninja/app/Services/Quote/SendEmail.php

<?php

namespace App\Services\Quote;

use App\Helpers\Email\QuoteEmail;
use App\Jobs\Quote\EmailQuote;
use App\Models\Quote;

class SendEmail
{
    public $quote;

    public function __construct($quote)
    {
        $this->quote = $quote;
    }

    /**
     * Builds the correct template to send
     * @param string $reminder_template The template name ie reminder1
     * @return array
     */
    public function run($reminder_template = null, $contact = null): array
    {
        if (!$reminder_template) {
            $reminder_template = $this->quote->status_id == Quote::STATUS_DRAFT || Carbon::parse($this->quote->due_date) > now() ? 'invoice' : $this->quote->calculateTemplate();
        }

        $this->quote->invitations->each(function ($invitation) {
            if ($invitation->contact->send && $invitation->contact->email) {
                $email_builder = (new QuoteEmail())->build($invitation, $reminder_template);

                EmailQuote::dispatchNow($email_builder, $invitation);
            }
        });
    }
}