29 CFR §38.79

1. (a)If a complaint does not contain enough information to identify the respondent or the basis of the alleged discrimination, the timeliness of the complaint, or the apparent merit of the complaint, the Director must try to get the needed information from the complainant.
2. (b)The Director may close the complainant's file, without prejudice, if:
   1. (1)The Director makes reasonable efforts to try to find the complainant, but is unable to reach him or her; or
   2. (2)The complainant does not provide the needed information to CRC within the time specified in the request for more information.
3. (c)If the Director closes the complainant's file, the Director must send written notice to the complainant's last known address, email address (or another known method of contacting the complainant in writing).