The Ames strain refers to something that is in widespread possession. You can go read definitive articles concerning this issue in the FreeRepublic anthrax site.
Something else here - this anthrax was processed into particles so fine they could pass through the paper of which the envelopes were made.
If this stuff were placed in the envelopes overseas, by the time they'd mailed the stuff it could well have all passed through!
See, the FBI is not telling us stuff that's important, e.g. the rate at which anthrax transpires through the envelope walls!
I think you are very wrong,
however,
I defer to Keri,
if she wishes
to join this discussion.