Sending bulk emails in PHP using Twilio SendGrid is a great method for keeping attendees informed about an event, as timely and detailed messages are necessary to avoid confusion. To accomplish this task, one must first set up a Twilio SendGrid account and install the required dependencies, including Composer globally installed and the SendGrid PHP library. The code to send bulk emails involves creating a new Mail object with a primary recipient, adding additional recipients using the Personalization class, and sending the email using the SendGrid API. The Personalization class allows for personalization of each email sent to individual recipients, making it possible to modify content based on their email address. Once the code is written, it can be tested by running the `php email.php` command in the console window, which will display a success message and the status code and headers from the email.