Attached image not show into body email

Hi experts,

I need to show image into body email, I'm doing it with class cl_document_bcs

     imagen = '<img src="cid:logofirma.jpg" align="middle" width="160" height="60"></img>'.

       APPEND imagen TO text1.

      document = cl_document_bcs=>create_document(

       i_type = 'HTM'

       i_text = text1

       i_subject = asunto ).

    atta_sub = 'logofirma' .

       CALL METHOD document->add_attachment

         EXPORTING

           i_attachment_type    = 'jpg'

           i_attachment_subject = atta_sub

           I_ATTACHMENT_SIZE    = len

           i_att_content_hex    = binary_content.

The image is displayed correctly in outlook, but in hotmail and gmail is shown as attached and does not appear in the body of the email.

Please help.

Best regards,

Robert.