I agree. :(
What's odd is that it only happens on Outlook 2011 for Mac! (I haven't upgraded to 2016 yet...perhaps this issue is fixed?). When I had Outlook 2010 and then 2013 on my former PC (before getting a new work computer), this wasn't a problem. So it's either
a Macintosh thing (that Microsoft doesn't have any control over) or it's a compatibility issue that Microsoft should remedy.
In any case....I just usually have to go into my Outlook Temp folder a few times each day in order to delete the temp files for whatever I'm needing to re-send? It was annoying at first but I'm used to it now. At least the folder clears itself after closing
Outlook! =/
In case it's helpful for anyone, you can access your Outlook Temp folder by opening up Finder, selecting "Go to folder" (under "Go" drop-down menu), and typing in "~/Library/Caches/TemporaryItems/Outlook Temp". Actually, I never have to
type it in anymore; my Finder remembers the pathway.
Half the time, the files are "locked" so that they can't be deleted. If that's the case, just right-click whatever temp files you want to delete and select "Get Info". From there you can uncheck the box next to "Locked". Then you can delete them.
;)