E-mail via Workflow task is not send they say aprox once a month

Question

Hi there
I am asked to check one system with a “workflow” running 2+ years. It is actually an task with method which sends an e-mail when Purchase requisition is created.
It istriggered by event in user exit(via function).
The version is IS oil 4.6C.
The problem is that e-mail is not send they say aprox once a month (which I personaly do not believe). However I have to do something (and explain what could be the reason).
What would be your idea to do?
I have in mind to subtye BUS2081 to e.g zz BUS2081 and then delegate bus2081 system wide(which is not done (but I think this will not solve the problem).
In addition all technical details:
I created event  ZCREATED for object ZABUS2105 (done as copy of BUS2105) in user exit MEREQ001 (EXIT_SAPLMEREQ_008) while creating purchase requisition via z transaction me51n and my colleague added this function in MV45AFZZ(while creating purchase order from sales order).
CLEAR EVENT_CONTAINER. REFRESH EVENT_CONTAINER.
i_banfn = IM_BANFN_NEW.
CALL FUNCTION 'SWE_EVENT_CREATE'
       EXPORTING
            OBJTYPE           = 'ZABUS2105'
            OBJKEY            = i_banfn
            EVENT             = 'ZCREATED'
                      creator           = sy-uname
       TABLES
            EVENT_CONTAINER   = EVENT_CONTAINER
This event triggers workflow task TS92000018
Task TS92000018 is a  background task and has  atribute »general task« . Metoda (program) is:
BEGIN_METHOD ZWF_SEND CHANGING CONTAINER. 
   call function 'ZWF_SEND_MAIL7XX'      
      Exporting                        
       banfn = OBJECT-KEY-NUMBER.                                                                               
END_METHOD.
Function Z_SEND_MAIL7XX:
FUNCTION ZWF_SEND_MAIL7XX.
""Local interface:
*"       IMPORTING
*"             REFERENCE(BANFN) TYPE  BANFN OPTIONAL
*"             REFERENCE(STATUS) DEFAULT 1
  DATA: reclist   TYPE STANDARD TABLE OF somlreci1  WITH HEADER LINE,
        objtxt    TYPE STANDARD TABLE OF solisti1   WITH HEADER LINE,
        objpack   TYPE STANDARD TABLE OF sopcklsti1 WITH HEADER LINE.
  DATA: doc_chng  TYPE sodocchgi1,
        tab_lines TYPE sy-index,
        subject   TYPE so_obj_des,
        email like zwf_emailko7XX,
        menge(17) TYPE c,
        I_Zwf_obdelan7xx like zwf_obdelan7xx,
        I_eban like eban  occurs 10 with header line.
        SELECT SINGLE * FROM Zwf_obdeLAN7xx into i_zWF_obdelan7xx WHERE
BANFN
EQ
BANFN.
  IF sy-subrc NE 0.
KONCNEMU
SELECT single * FROM eban where banfn = banfn.
    SELECT single * FROM zwf_emailko7XX into email
                    WHERE  ekgrp = eban-ekgrp.
refresh reclist.
    reclist-receiver = email-SMTP_ADDR.
    reclist-rec_type = 'U'.
    APPEND reclist.
CONCATENATE text-015 banfn INTO subject SEPARATED BY space.
  doc_chng-obj_name = 'SENDFILE'.
Mail Subject
  doc_chng-obj_descr = subject."text-001.BO22.11.2005
Mail Contents
refresh i_eban.
  CONCATENATE text-015 banfn text-016 sy-mandt text-017 eban-ernam INTO
objtxt
SEPARATED BY
space.
    APPEND objtxt.
select * from eban into i_eban where banfn = banfn.
menge = i_eban-menge.
  CONCATENATE  i_eban-matnr i_eban-txz01 menge i_eban-meins INTO objtxt
SEPARATED
BY space.
  APPEND objtxt.
  append i_eban. clear i_eban.
endselect.
  DESCRIBE TABLE objtxt LINES tab_lines.
  READ TABLE objtxt INDEX tab_lines.
  doc_chng-doc_size = ( tab_lines - 1 ) * 255 + STRLEN( objtxt ).
  CLEAR objpack-transf_bin.
  objpack-head_start = 1.
  objpack-head_num = 0.
  objpack-body_start = 1.
  objpack-body_num = tab_lines.
  objpack-doc_type = 'RAW'.
  APPEND objpack.
  CALL FUNCTION 'SO_NEW_DOCUMENT_ATT_SEND_API1'
       EXPORTING
            document_data              = doc_chng
            put_in_outbox              = 'X'
       TABLES
            packing_list               = objpack
           object_header              = objhead
           contents_bin               = objbin
            contents_txt               = objtxt
            receivers                  = reclist
       EXCEPTIONS
            too_many_receivers         = 1
            document_not_sent          = 2
            operation_no_authorization = 4
            OTHERS                     = 99.
insert into zwf_obdelan7xx values banfn.
commit work.
endif.
ENDFUNCTION.

Answer 1

There are several things you can check before starting to check the code/solution.
I would start by sending an e-mail from SAP Business Workplace - either to someone who say he/she receives e-mail only once a month, or to yourself if that is not possible. Check how long it takes from the mail is sent until it is received. Once the first mail has been received, send another mail and check the time again (to determine the sendmail process' interval). Of course you can probably just check the configuration of send processes ... but you may as well give them some hard proof.
Secondly, check the send log (transaction SOST) - and find out how often there are the type of messages you are interested in. Alternatively, test the workflow and verify that messages are sent immediately.