If y’all find a Pony artist’s Tumblr links point to a deleted blog, do the fandom a favor and immediately register the blog name as a side blog if possible and make the only post a link to whatever active site they have now; a poop-ton of old school fan artists who wandered away from Tumblr or from the fandom in general had their defunct blog names snatched up by scumbag spam campers and porn spam blogs.
I have a couple of empty blogs registered with throwaway emails that I keep solely to snatch up abandoned fan art blog names when they become available, just to keep spammers away from them.