I was having a bit of a problem today. I could not login ot a test account I had and i know I had the login information in one mail somewhere.
Problem was that I did not know in what mail, and not even exactly when. So i was going to search.
But in this new version of thunderbird I could not select Body as a field to search in.
Until i found out that you you have to click in “Run search on Server” in the top of the search windows.
Took some time to found that.