If you just want to get on with things, just delete the piece of mail. If you want to file a complaint, look at the full headers of the message to find out where the mail originated. The CIT Help Desk can assist you to display and interpret the full headers which should help identify or verify the domain from which the mail originated. The text of the objectionable message, and the full headers of the message, also should be included with the complaint. Don't be fooled.
Spammers have many tricks.
Use filters if your mail program provides them. The CIT Help Desk can assist you in setting up filters.