Export side you obviously can't control :( But on import, if you use Data -> From Text, and on Step 3 select all the columns and make them "Text", that will pre

Export side you obviously can't control :( But on import, if you use Data -> From Text, and on Step 3 select all the columns and make them "Text", that will prevent Excel from mangling any of the data (stripping leading zeros, evaluating strings starting with = as formula etc.)