I recently inquired about a job posting at another company by sending a message via LinkedIn to a former acquaintance that now works for the company. From the job posting's description and individual's title on LinkedIn, it appears that he would be the supervisor for this new job. Because this position is somewhat outside of my current field, I wasn't sure if someone with my experience would even be considered; instead of formally applying for the job I attached my resume to a LinkedIn message and essentially asked "would someone with this resume be considered?".
I never heard back from him, but I'm quite certain he saw the message due to the LinkedIn messaging app stating that the message was read and a few days later the job posting disappeared.
This complete lack of even a cursory response surprised me and makes me wonder if I made some faux pas. Is it acceptable etiquette to inquire about a job posting and send your resume to a prospective supervisor outside of the normal applicant submission channels?