This hoax is not new but there has been a major second wave in the last few days.
There are three separate issues.
1) The real sulfnbk.exe file that is used by Windows is located in the C
Windows\Command folder. Don't delete it.
2) The virus/worm W32.Magistr.24876@mm often is delivered as an attachment named sulfnbk.exe. If this file arrives as an attachment to an email message, then the file is undoubtedly infected. Do not run it. Dispose of it - there is no reason for anyone to send such a file.
3) Then there is the (clever) sulfnbk.exe email hoax. It is sent by someone you know (who doesn't know he is sending it). It says that he has been alerted to malware called sulfnbk.exe that McAfee and Norton cannot find. He states that he found this "virus" file on his PC even though virus checkers overlooked it and that it must be disposed. Ha! If Norton or McAfee does not find a virus in your sulfnbk.exe that is because there is none. Don't discard the file, disregard the hoax.