“I wonder how the system would cope with millions or billions of e-messages in one day or week that all raised flags?”
Fact is that, if millions knew of the “word of the day or week”, that the government would also know about it, and disregard it as just an inconvenience.
If what the NSA says is true, it’s the pattern of communications that they’re after, and not some gimmick by someone to send them off track. A one day intrusion into the system is not a pattern for a one suspect or a suspicious group.
You don`t have to use the same word, in theory, any word that kicks the system into gear would work, two or more in the same message would be even better.