Hi Irene,
When you are working with Incident Management Interactive forms there are few check points for receiving/testing the mails with attachments.
Check Point #1: See the inbound processing configurations in the SCOT->Settings->Inbound Message->Inbound processing or you can do the same from SPRO->SAP EHS Management->Incident Management->Print Forms and Interactive forms->Define Inbound processing for emails.
Check Point #2: After submitting your form, see if your able to see the log in SLG1 transaction for the object "EHHSS_BO_INC", if you see a log either success or error that means you received the mail to SAP, if you dont see any log that means SAP didnt received the mail.
Check Point #3: If the inbound processing fails because of the any reason and if you can see the log in SLG1, then you can test the form manually from SAP using the below program "R_EHHSS_TEST_FORM_INBOUND".
Thanks
Sagar Pilli