Essentially no spam comes from juno.com itself, but a great deal of spam
is _forged_ to look like it came from juno.com (or hotmail.com, or
aol.com, or several other popular domains) but is sent through other
systems. The web-based interfaces for juno.com and hotmail.com make
spamming through them rather difficult, and those domains do have a good
record of dealing with not just the few spammers who spam from them, but
even the accounts of spammers who try to use juno.com or hotmail.com
mailboxes for reply addresses.
Rule #1 of tracing spams: Don't even bother looking at the From:
header. These days it's always forged.