I want to know if what I'm doing is legal

I signed my mom up for a cleaning job and a lady emailed me back with information and telling me she was going to send a check of $500 to show how serious she was about the job being done. The next day she emails me telling me her secretary made a wrong check and send a check of $1,950 instead and if I could deposit it to my bank account 6take $550 for me and send the rest to the painter using Western Union. The problem is that I find it hard to believe someone would send that much money through a check trusting me plus the check isn't even a personal check, no information about her at all.