At the very top of the "suicide" tag page, there's this message: "If you or someone you know is dealing with an eating disorder, self harm issues, or suicidal thoughts, please visit our Counseling & Prevention Resources page for a list of services that may be able to help."Tumblr is the first social media website to actively attempt to prevent suicides, and its community reflects this.
Then, there's the community itself. If anyone posts about feeling suicidal or depressed, there will almost always be a slew of messages from their followers, even from people they've never spoken to before, trying to cheer them up or offer them a shoulder to cry on.
In fact, a good amount of Tumblr blogs are dedicated to this, pegged as "recovery blogs" or "feel-good blogs". Basically, these blogs are run by people who, while still utilizing Tumblr for their needs, are there as often as possible for others to come to when they need to talk or vent. Naturally, they can't help with every problem, but they will try.
Similar to the above, tumblr recently made it so that searching "thinspo" brings up a page that asks if you or someone you know is struggling with an eating disorder and provides helpful links.
As well, searching "blood" as one of the tags leads to a page asking if everything is alright and gives you a number to call if you or someone you know has issues with self-harm.
As cliché as it may sound, some users really do love their followers and the users of the blogs they follow. If any of their loved Tumblr ones start receiving hate, they will gladly lend a hand in shutting it down.