Hey Michael,
I'm in exactly the same situation. I have been waiting since the 4th of November and have been trying to get billing support to help.
Ali from billing support just told me that "the mail API is not fully supported any longer, therefore we ask that you try to work with third party solutions such as SendGrid[1] or MailGun[2] as a recommended workaround"
This is news to me.
It's nice that they are doing free advertising for SendGrid and MailGun, but If my quota is not increased soon I'll have to use one of my other app engine apps to send email for the new one. (My other main app is sending about 2k email a day.)
Adam, if you are still out there, I would love some help too!
Jay.