Hi Amine,
Yes you can send email to multiple recipients using FM 'SO_NEW_DOCUMENT_ATT_SEND_API1'.
ls_reclist-receiver = 'abc@gmail.com'.
ls_reclist-rec_type = lc_int.
APPEND ls_reclist TO lt_reclist
ls_reclist-receiver = 'xyz@gmail.com'.
ls_reclist-rec_type = lc_int.
APPEND ls_reclist TO lt_reclist
CALL FUNCTION 'SO_NEW_DOCUMENT_ATT_SEND_API1'
EXPORTING
document_data = ls_docdata
put_in_outbox = abap_true
commit_work = abap_true
TABLES
packing_list = lt_objpack
contents_bin = lt_objbin
contents_txt = lt_contents_txt
receivers = lt_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.
Thanks
Sri