My Android Galaxy S4 won't let me mark e-mail as spam

[AC Question]

I have received four new e-mails from the same spammer. When I try to mark any of them as spam, the "mark as spam" link is greyed out. I can mark other e-mails, but not these. They have also been spoofed so the sender e-mail is the same as mine, except the domain name is @netscape.net

Is the spam blocking not working because this is a spoofed e-mail address? What can I do, besides throwing each of them into the trash.