Sending taxes in the US by mail was unnerving for me, I don't know if things have changed but basically you put the envelope in the mail box and then .. you don

Sending taxes in the US by mail was unnerving for me, I don't know if things have changed but basically you put the envelope in the mail box and then .. you don't know, no receipt from the IRS, nothing. What happens if the envelope is lost? In all the countries I've lived you submit your taxes and you get and instant receipt or acknowledgement.