Send attachments using SMTP

Hi All,
I would like to know step by step procedure of how attachments can be sent using in-built SMTP service.
If a sample service can be provided it would be more helpful.

Its pretty straight forward to test.simply inputs to the client:smtp service and under the attachments (map convert to bytes or string to the content and set Content-Type (text/plain or text/html or text/xml or MIME related) and specify filename for attachment)