I sent the above e-mail to Tumblr (firstname.lastname@example.org) this evening. I just received the following response:
I can’t tell you how much we value your support and feedback. We really appreciate you taking the time to let us know about this, and we’ll share your request with the rest of our team.
Please let me know if there’s anything else I can help you with.
Tumblr.com / Photoset.com Support.
I would urge all of you artists, models, photographers and other contributors/posters of original content to send similar messages, as this is an issue which affects all of us and which should be remedied.
There is no reason why anyone should be able to reblog the work which we worked so hard to create and then either remove credits or pass the work off as their own.
Of course, people will always be able to steal our work but I think the modification that I have requested would certainly reduce the number of reblogs that delete our credits.
Please reblog this post AND, if you’re inclined, send an e-mail to Tumblr support to join in my request for this modification.