And then thirdly, there is mail from unknown sources.
How websites can block code from unknown sources.
"Suffolk does not accept research funds from unknown sources," the spokesman said in an email.
Resist the temptation to buy drugs on the Internet or from unknown sources.
Unsolicited mail from unknown sources "doesn't even make it out of the mailroom," said Adam Rothberg, spokesman for Simon & Schuster.
Bits of costume are sold at every corner shop, scraps of brass-band music lilt from unknown sources.
For some books, including the Psalms, Origen presented as many as three additional Greek texts from unknown sources.
Users must be very careful about the risks involved with using applications and programs from unknown sources.
The best way to avoid infection, experts advised, is not to open e-mail attachments from unknown sources and to keep antivirus software up to date.
The truth is that Britain has become a place where untransparent money, from unknown sources, is widely accepted with a complacent shrug.
(The administration has said nothing thus far about whether current cyberattacks from unknown sources on the Iranian nuclear program's computers would lengthen these estimates).
