Wow, As easy as that. I followed your directions and Bingo, all fixed and working like it should. Thanks heaps, you stopped me pulling out the rest of my hair.
I had the same exact problem for 16 months. It started after I attempted to send an email - while driving thru an urban area - via an unrecognized public wi-fi,(with smart-switching turned on) - while I was in a cell service dead zone. My phone started exhibiting all the symptoms everyone has described...including rapid battery drain. I studied virtually every help site and forum...only to conclude that there is NO quick fix or simple solution. Believe it or not - I actually did a full factory restore on the phone - and that didn't fix it.
Here's what will: a combination of all procedures already mentioned. Suck it up and delete all existing email and exchange accounts. Clear all caches. Remove and reinsert battery. Reboot.
You'll then have to reconfigure all your emails from scratch.
For those that say I have to go Applications and "clear data" on my email exchange on phone, does that clear my email forever on my main computer at home? I am trying to clear a "sending failed" email that keeps coming back on my phone that I cleaned my outbox already months ago. It's so frustrating as I know it's probably using data to "looking for a non-existing email" and also it is bothering me that it keeps showing up on my notifications as "sending failed". Hope that makes sense. I have Comcast and use it through Outlook and so if I have to delete both and put back on my phone again I don't mind I just want this to be cleared! I also don't want to lose my emails that are in my inbox from the main computer. Please reply. Thanks
Hen the failed sending shows. Give the icon a long press to open the app. Clear the data and clear the cache. Restart your device. This should clear the notification. If not. Stop the app reinstall email address. This will clear the notification