Hi Monika
If I've understood what you mean, you need to pick up email (so outlook file), convert it to pdf format and attach it to PO by GOS.
I don't know if there's a tool in SAP to do it, you can considere it can attach the email (so in outlook format) without any convertion.
Else you can try to use an external program (a pdf converter) in order to convert the file and so to attach it
Max