概要

アドオンプログラムでメール送信を行うには送信先、送信元、メールタイトル・本文、添付ファイルの
パラメータを汎用モジュール：SO_DOCUMENT_SEND_API1に渡す事で実現可能。
送信元が実行ユーザーでよい場合は汎用モジュール：SO_NEW_DOCUMENT_ATT_SEND_API1でも可能だが、
正直何の違いがあるか不明。

サンプルコード：メール送信

* Sender
DATA: v_sender     TYPE soextreci1-receiver,
      v_sender_typ TYPE soextreci1-adr_typ.
v_sender = sy-uname.
v_sender_typ = 'B'.
*v_sender = 'Sender@xxx.com'.
*v_sender_typ = 'SMTP'.

* Reciever
DATA: it_reclist    TYPE somlreci1 OCCURS 5 WITH HEADER LINE.
it_reclist-receiver   = 'Receiver@xxx.com'.
it_reclist-rec_type   = 'U'.
it_reclist-com_type   = 'INT'.
it_reclist-notif_del  = 'X'.
it_reclist-notif_ndel = 'X'.
it_reclist-express = 'X'.
APPEND it_reclist.

* E-mail Header
DATA: v_doc_data     TYPE sodocchgi1.
v_doc_data-obj_descr = 'E-mail Title'.

* E-mail Body
DATA: wa_body TYPE soli,
      it_body TYPE soli_tab.
wa_body = 'E-mail body 1 line'.
APPEND wa_body TO it_body.
wa_body = 'E-mail body 2 line'.
APPEND wa_body TO it_body.

DATA: it_packing_list LIKE sopcklsti1 OCCURS 0 WITH HEADER LINE.
it_packing_list-transf_bin = space.
it_packing_list-head_start = 1.
it_packing_list-head_num   = 0.
it_packing_list-body_start = 1.
it_packing_list-doc_type   = 'RAW'.
DESCRIBE TABLE it_body LINES it_packing_list-body_num.
it_packing_list-doc_size   =  it_packing_list-body_num * 255.
APPEND it_packing_list.

*Attached file
DATA: it_file     LIKE solisti1 OCCURS 0 WITH HEADER LINE,
      it_file_hex TYPE solix_tab,
      v_filesize  TYPE i.
it_file = 'Attached file line 1'.
APPEND it_file.
it_file = 'Attached file line 2'.
APPEND it_file.

CALL FUNCTION 'SCMS_TEXT_TO_BINARY'
  IMPORTING
    output_length = v_filesize
  TABLES
    text_tab      = it_file
    binary_tab    = it_file_hex
  EXCEPTIONS
    failed        = 1
    OTHERS        = 2.

it_packing_list-transf_bin = 'X'.
it_packing_list-head_start = 1.
it_packing_list-head_num   = 1.
it_packing_list-body_start = 1.
it_packing_list-doc_type   = 'txt'.
it_packing_list-obj_descr  = 'filename'.
DESCRIBE TABLE it_file_hex LINES it_packing_list-body_num.
it_packing_list-doc_size   =  it_packing_list-body_num * 255.
APPEND it_packing_list.

* Call Function module
CALL FUNCTION 'SO_DOCUMENT_SEND_API1'
  EXPORTING
    document_data              = v_doc_data
    sender_address             = v_sender
    sender_address_type        = v_sender_typ
    commit_work                = 'X'
  TABLES
    packing_list               = it_packing_list
    contents_txt               = it_body
    contents_hex               = it_file_hex
    receivers                  = it_reclist
  EXCEPTIONS
    too_many_receivers         = 1
    document_not_sent          = 2
    document_type_not_exist    = 3
    operation_no_authorization = 4
    parameter_error            = 5
    x_error                    = 6
    enqueue_error              = 7
    OTHERS                     = 8.

説明

document_data：ヘッダ的な情報
sender_address：送信元の情報(ユーザーID、メールアドレス等)
sender_address_type:送信元の情報(ユーザーIDの場合’B’、メールアドレスの場合’SMTP’、他多数有り)
packing_list:本文と添付ファイルの情報
contents_txt：メール本文
contents_hex：添付ファイル
複数送信したい場合は、作りたい文だけpacking_listを追加していけばいけそうだけど未確認