Turning that option off simply prevents the store from saving copies of outgoing emails. The option is normally off by default, partly because it generates a lot of content, and balloons your storage requirements significantly especially in busy stores. And, since most storeowners seem to have the store send them copies of all the emails anyway it's really not necessary except maybe if you're trying to troubleshoot a problem for a particular recipient who's complaining about not receiving emails.
So, in short, leaving that off is probably not a bad idea.

But, I'm still bothered that there's even a problem with that table. Your hosting company should really take a look at the database and fix up that table, even if it means rebuilding it (via a simple export of structure only, then drop and recreate using the exported sql text).