I also learned to determine the size of the company as well. Larger more organized structures maintain email address consistentcy, meaning if joe the janitor has firstname.lastname@example.org
then the CEO email address is set up the same way. But smaller companies may be a little more diverse meaning joe's email may be email@example.com
but the CEO (john doe) may be firstname.lastname@example.org
. So I get ready for some bounce backs and have alternate email addresses lined up.
Also to add after the normal routes, I also tend to put one more level in there before going completely to the top with the CEO. I try to find out if there is an operations or support VP or similar position and email that person and give them a chance to correct their departments deficiency and respond to me first. If I don't hear anything then, then I include that lack of exchange in my email to the CEO which is CC'd to everyone else.