The SMTPMailAttachmentSignatureService allows and application to send a single email attachment and a digital signature.
The SMTPMailAttachmentSignatureService supports the following commands:
5.27.1 SERVICE_LOAD
5.27.2 SERVICE_GET
5.27.3 SET
5.27.4 RESET
5.27.5 SEND
5.27.6 SERVICE_UNLOAD
