It can take a while for someone to respond to a message.
There's this job I'm interested in, and I'm still waiting for a response. (I've been waiting for days now) I do however have an old school friend who works there. So I was wondering if I should contact her or not, in case the employer never checks their email. What do you think?
If you trust your friend, than absolutely.
Personally, I’d contact the employer directly by phone. Introduce yourself, say you’re really interested in the role and ask if there’s an update. I’ve done this three times before and in two cases, got an apology for the delay and an interview invite; and in the other, an apology for the delay and the autogenerated reject letter.
At least either way you’ll know; and if you haven’t got the job, would have let the employer know you’re interested in future roles.