public class SendVF_Email_InvocableMethod {

    @InvocableMethod(label = 'Send an email from apex class'description= 'sends an email')
    public static void sendEmailWithAttachment(List<id> listofInvoice) {
        for (Id Invoiceid : listofInvoice) {

            PageReference pref = page.selected_invoice_pdf;
            pref.getParameters().put('id', (Id) Invoiceid);
            pref.setRedirect(true);

            Attachment attachment = new Attachment();
            Blob b = pref.getContentAsPDF();
            attachment.Body = b;
            attachment.Name = Datetime.now().format('yyyy-MM-dd HH:mm') + ' ' + 'Invoice' + '.pdf';
            attachment.IsPrivate = false;
            attachment.ParentId = Invoiceid;
            insert attachment;

            Messaging.SingleEmailMessage semail = new Messaging.SingleEmailMessage();
            Messaging.EmailFileAttachment attach = new Messaging.EmailFileAttachment();
            attach.setBody(pref.getContentAsPDF());
            semail.setSubject('Invoice Issued');
            String[] emailIds = new String[]{};
            for (Invoice__c i : [
            SELECT Billing_Contact_Email__c
            FROM Invoice__c]){
            emailIds.add(i.Billing_Contact_Email__c);
            }
            String s = String.join(emailIds, ', ');


            String[] ccAddresses = new String[]{'someaddress@email.com'};
            for (Invoice__c i2 : [
            SELECT Billing_Contact_Email_2__c
            FROM Invoice__c]){
            ccAddresses.add(i2.Billing_Contact_Email_2__c);
            }
            String s2 = String.join(ccAddresses, ', ');

            semail.setToAddresses(emailIds);
            semail.setCCAddresses(ccAddresses);
            semail.setBccSender(true);
            semail.setReplyTo('billing@email.com');
            semail.setSenderDisplayName('billing@email.com');
            semail.setHTMLBody('<p>Hi' + Invoice__c.Billing_Contact_Name__c +',</p><p>Attached please find your invoice from Company for your review. If you have any questions please contact billing@email.com<br /> <br />Thank you for your business!<br /> <br />Sincerely,<br />analytic.li Billing Team<br /> <br />P: (XXX) XXX-XXXX<br />E: billing@email.com</p>');
            semail.setFileAttachments(new Messaging.EmailFileAttachment[]{attach});
            Messaging.sendEmail(new Messaging.SingleEmailMessage[]{semail});
        }
    }

}