Customarily, you'd send a PDF/X-1a file with fonts embedded by simply saving that format (with crops and bleed), therefore outlining type would actually not always be a good thing. PDF/X-1a is often preferred because it is a self-contained format with fonts embedded and artwork flattened. This ensures the most accurate preproduction.

If you are sending a .eps or .ai file, then outlining type is the best practice.

Should I turn the text on my poster to outlines before I print?
In Esther 7:4 we read


  וְאִלּוּ לַעֲבָדִים וְלִשְׁפָחוֹת נִמְכַּרְנוּ, הֶחֱרַשְׁתִּי--כִּי אֵין הַצָּר שֹׁוֶה, בְּנֵזֶק הַמֶּלֶךְ ...
  
  ... But if we had been sold for bondmen and bondwomen, I had held my peace, for the adversary is not worthy that the king be endamaged.


Is this true? Had, in fact, the entire Jewish population been sold as slaves Esther would not have said a word about it? Is this simply hyperbole? How do we understand this? 
