OK, I've figured out what made it change on my GS3. There is a file in [root]/system/csc called feature.xml. You need to be rooted to edit this file. Previously, I had edited it to change a camera setting to enable the Shutter Sound menu item, which for some reason Sprint disables on their phones. (see this thread if you're interested:
http://forums.androidcentral.com/sp...ow-turn-off-your-shutter-sound-2-minutes.html)
Anyway, recently (like on 2/14), I edited this file again, to try to enable the ability to take a picture while on a phone call. Another setting which Sprint, for some reason, disables. (see this thread, if you're interested:
http://forums.androidcentral.com/verizon-galaxy-s-iii/188817-unable-take-pictures-when-call.html)
So, I edited the file and rebooted the phone so the changes would take effect, but I still couldn't take pictures during a phone call. Not really a big deal to me, so I didn't think much of it.
Tonight, it dawned on me. Editing the file in ES File Explorer changes the permissions on the file. The system could no longer read the features.xml file at all. So I went in, changed the permissions to rw-r--r--, rebooted the phone, and now I can take pictures while on a call. What does this have to do with my email background, you're wondering? Patience, grasshopper.
Shortly thereafter, I checked my mail, read a new message, exited the email app, and went "Whoa!" Back into the email app, and it's now white on black again! So, back into the features.xml, file, scroll down, and down, and down, skimming through the entries, and all the way at the bottom come to a section labelled " <!--Email-->. Sure enough, one of the settings in there is "UseFixedBgColorAsWhte" and the value is True. With the read permissions messed up, the system couldn't read this value, and apparently defaults to black. I may try setting it to False and see if the email program then give me an option to set the background color.
Another interesting sounding option in the Email section is "EasDisableOptionSyncInterval" which is set to True. Setting it to false should enable that option, I think. Right now, the phone gives me 6 options for sync interval, including Push and Manual. I wonder what it will show if I set this to False. (Eas implies this is only for Enterprise Active Sync accounts.)
Sorry for the long-winded explanation. If you're rooted, and adventurous, you might want to read through this file. There are a ton of options set there. I would strongly, very strongly, suggest making a backup before changing anything. And remember to make sure the file permissions are set correctly (rw-r--r--) before rebooting your phone. If you don't understand what this means, and don't have at least a vague familiarity with the syntax of XML, you probably want to avoid messing with this file.
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