PS. They've just been bought by Yahoo!
We are making improvements to the way we serve our custom domain traffic and we
need you to update your settings before June 21.
Please point your custom domain to Tumblr's IP: 188.8.131.52
If you do not make this update by June 21, your custom domain will no longer
redirect to your blog.
To learn more about how to do this, check out our custom domains help page
Your friends at Tumblr
P.S. We previously sent this email without the IP address. Apologies for the
double email. We <3 you!
Tumblr's offices are located at East 21st St, 10th Floor. New York, NY 10010.