Has anyone gotten or heard of an email form MailScanner <[email protected]>

I just received an email from this person which read:

A message you recently received from "<[email protected]>" with the
subject "Current Microsoft Critical Pack"
contained one or more viruses that could be disinfected.

The viruses have been removed, and the disinfected files are attached
to this message.
--
MailScanner
Email Virus Scanner
It also had an enclosed attachment which my virus protection software did not read as a virus.
NO, I did not open it..... just wondering

Another stupid question: Can a virus infect ones computer if you just open an email, without opening the enclosed attachment?