It does not sound legit. It's a funny oddity that these spammers only want days in August!! I do not and will never again list my property on Craigslist. It is prolific with spammers and you will more than likely find you property pictures and descriptions weeks or months from your actual posting on another ad. If you do choose to continue to advertise on CL, you need to check every single day for your property to pop up in another ad. It's not a question of it, it's a question of when.
You can run a search above and just put in spammer, spam, Ukraine and you will get a ton of reading material on these persistent spammers.