When candidates apply to your role they already receive a notification letting them know the resume has been received.
Bulk emailing is not currently supported by Betterteam. Feedback from candidate surveys we have done has shown that no response is actually better than sending bulk, impersonal, rejection emails.
If you have other bulk emails you want to send candidates you can do so from your email client. Most email clients support bulk replies.
Another option is to upgrade to the VIP plan which allows you to download all your applicants in a CSV. You can then import them into a mailing system like Mailchimp.