Since the last one or two updates, Global search no longer reliably finds all the the matching messages in folders that are marked for global search access. I have had to resort to using the right click search on individual folders to find what I need to find (even if only in header fields of messages) which is a lot more tedious. Please fix this, restore it to its previous working order or remove the feature.
It is dangerous to have a search function not find search terms when it should giving us the WRONG impression that its not to be found when it truly exists. I deal with a lot of email in over 15 email accounts and need to be certain when I can or can't find an email response from someone. Email is serious communications and can't afford problems like this.
Note the only reason I use thunderbird is to use the portable version. I will not use an email solution that can't be copied from one computer and run where-ever I copy it to.
Before you start telling people things need to be fixed, help the devs here figure out if it can actually be fixed on their end.
The best way to do this is test this functionality on a local (as in non-portable) install of the app. If the problem also occurs on a local install as well as the portable version, you are in the wrong place, and should be reporting this to Mozilla themselves as it is a problem with the base app. If it does not happen with a local install, then it would fall in the realm of this site and it's Dev team.
Are you searching inside "Filter these messages... <Ctrl+F>" instead of "Search all messages... <Ctrl+K>"?
superdml,
which release numbers are you referring to when you say "Since the last one or two updates, Global search no longer reliably find ..." ?
As far as I know, the 3.1.x series of updates have no injected any such issues.