I have just installed Thunderbird portable to a 8GB USB2 flash drive. I have copied all the local files as detailed here...
https://portableapps.com/support/thunderbird_portable#local_profile
My mails total about 4GB split across various folders.
However, when I launch Thunderbird portable edition and click on any of my larger folders it simply shows 'building summary file...' at the bottom left and seems to hang...
Is this what is meant by "Sometimes, certain profiles will cause the launcher to fail or hang. In that case, start from scratch and try just copying your mailstores (Mail and ImapMail directories) as well as your prefs.js and abook.mab files." ?? From reading that I thought it wouldn't even get to the stage I am at?