CBS Emergency -- Suspicious Letter Targeted Individual Connected to "DWTS"

The suspicious letter containing white powder that triggered a crisis at CBS Studios today was addressed to a specific individual connected with "Dancing with the Stars" ... TMZ has learned.

While there's been controversy surrounding Chaz Bono's appearance on the show ... sources tell us the target was NOT an on-air personality or contestant.

As we previously reported, it was determined the powder in the letter was not a harmful substance.