Hello Victor Enzo Montenegro,
I was having hard time making customization to read the Invoice Attachment through Email channel after spending 2 days of times on ECC6.0 EHP5. I could not figure out what was going wrong. So Coded ABAP program that will full fill the purpose. May those customized are more for SRM Specific. This video demonstrates how it is achieved.
Please shoot me an email so that I send you the raw code while I am still tweaking it to publish on SCN.
Thanks,
Kolusu