I have implemented a platform using rails, and the goal is to send thousands of emails to customers with one click. The concept is that an email array runs each loop and inside each loop runs send email functionality like below.

@emails = ['abc@gmai.com', 'abc@example.com'] # More than 3 thousands

@emails.each do |email|
    aws_email_sender(email, @email_subject, @email_body_html)
end

And the email function is like below:

def aws_email_sender(recipient, subject, htmlbody)
    sender = "hello@example.com"

    awsregion = "ap-west-1"


    # The HTML body of the email.
    htmlbodycontent = "#{htmlbody}"

    # The email body for recipients with non-HTML email clients.  
    textbody = "This email was sent with Amazon SES using the AWS SDK for Ruby."

    # Specify the text encoding scheme.
    encoding = "UTF-8"

    # Create a new SES resource and specify a region
    ses = Aws::SES::Client.new(region: awsregion)

    # Try to send the email.
    begin
        # Provide the contents of the email.
        resp = ses.send_email({
            destination: {
                to_addresses:  [recipient]
            },
            message: {
                body: {
                html: {
                    charset: encoding,
                    data: htmlbodycontent
                },
                text: {
                    charset: encoding,
                    data: textbody,
                },
                },
                subject: {
                charset: encoding,
                data: subject,
                },
            },
            source: sender,
        });

    
    # If something goes wrong, display an error message.
    rescue Aws::SES::Errors::ServiceError => error
        puts "Email not sent. Error message: #{error}"
    end
end

The email is sending well by AWS but my rails application has gone down like

A timeout occurred, error code 524

I couldn't get the breaking point, why has my application gone down every time?

Thanks in Advance