I thought this would help someone in case they didn't know how to undo “always display images from this sender” on Android GMail.
Within my GMail app on my Android phone, I accidentally clicked on the tiny link to display images for one of my stealths. The email happened to be from Paypal. So, I thought, great...now all the Paypal logo's are showing. This is of course, a web beacon, that would take me directly to my PP account if I mistakenly clicked on it.
I have multiple GMail accounts for various stealths and I noticed all other PP emails were also displaying images across these stealths.
I logged into a computer and checked the
same account from the
same PP sender and it did not display the image (on the web interface, the option to display external content was still unchecked).
The problem seemed isolated to just how the images displayed on the phone using the GMail App.
After some playing around, here's what I found you need to do...
From the Main Inbox or inside any email:
1. Bring up the Menu --> Settings --> General Settings
2. Now click the Menu button again to bring up sub-menu of options
3. Select
Clear picture approvals.
This will clear all approved sender images that were previously approved. Not sure if there is an individual way to do this, but this method works perfectly for GMail app on Android.
Hope this saves someone a bit of headache, as it took me some time of playing around w/ the phone to find this hidden setting
How do I undo “always display images from this sender” on Android GMail? 
