First, do not use mozbackup. Even the mozback website says to not use. TRANSFER::: Here is the link for moving a profile in Windows when installed in default location:

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

here is the info in brief steps:

1. ensure thunderbird is not running on old machine
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media
5. ensure thunderbird is installed on second computer and NOT running
6. enter %appdata% in search window on task bar and press Enter key
7. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
8. start thunderbird and all should be there

This process copies everything that is in the profile. Be sure that thunderbird is NOT running on either PC.

Thank you - I'll do a mega backup and transfer at the weekend. I'm not so worried about the Current folders since they are all IMAP so should be preserved - is that right? Can you reassure me that all the Local Folders will also be transferred across? Do I need to do any compacting, and should I do this before or after transfer? Sorry to be so cowardly, I am terrified of losing material.

Also, can I install 64-bit on the new laptop and copy over the old 32-bit profile? If not, is there any problem in continuing to use a 32 bit Thunderbird? I am getting a lot of hanging/not responding in the current TB. Note I'll upgrade to 5.2esr before I do that. Do you know if the hanging problems are less with version 5.2?

again huge thanks

Kate

Copying with windows file explorer will ensure that every character is copied, but be sure that thunderbird is not running or some data will be missing. I suggest emptying trash and junk and compacting to reduce the profile size. You're right, that IMAP will self-restore if needed. I am not familiar with 32-bit, but the profile is just data, not software. On restarting on new PC, if there is an incompatibility message, exit and look for a compatibility.ini file in profile and delete it. Keep the old PC until all is stable. Sometimes, an error or oversight happens during transfer. In such rare instances, though, any missing data on old PC can be copied and replaced piecemeal with windows file explorer. Once everything is working, I suggest using same copy steps to create a backup. And do that regularly. If you encounter a problem, don't act quickly; pause and let us know. This transfer is a no-braining 99% of the time. :)

Thank you - rest assured I'll be straight back here if I have any problems!

all very best wishes

Kate