I think part of the problems you point to (though not all) could be easily fixed by just simple tweaks to the initial email: In the initial email, say when you plan to post by if you don’t get a response (include that in bold) and say something to indicate how much back-and-forth you’re ok with /​ how much time you’re able/​willing to invest in that (basically to set expectations).
I think you could also email anyone in the org out of the set of people whose email address you can quickly find and whose role/​position sounds somewhat appropriate, and ask them to forward it to someone else if that’s better.
I think part of the problems you point to (though not all) could be easily fixed by just simple tweaks to the initial email: In the initial email, say when you plan to post by if you don’t get a response (include that in bold) and say something to indicate how much back-and-forth you’re ok with /​ how much time you’re able/​willing to invest in that (basically to set expectations).
I think you could also email anyone in the org out of the set of people whose email address you can quickly find and whose role/​position sounds somewhat appropriate, and ask them to forward it to someone else if that’s better.