Hi Harsh,
If you want user to directly open link.
CALL METHOD cl_gui_frontend_services=>execute
EXPORTING
document = l_url_doculink
EXCEPTIONS
OTHERS = 1.
Give URL and sharepoint folder will open directly.
For sending attachements through proxy, check below:
Step by Step guide to develop Outbound ABAP Proxy with PDF attachment. - ABAP Development - SCN Wiki
Thanks,
Anil