scheduleEmail(email) {
        return this.#jobsService.addJob({
            name: 'batch-sending-service-job',
            job: this.emailJob.bind(this),
            data: {emailId: email.id},
            offloaded: false
        });
    }
Schedules a background job that sends the email in the background if it is pending or failed.
@param {Email} email
@returns {void}