A long time ago, say C2004 I had a thunderbird install on my old K6, but I lost access to the computer, and it took ages before I had the datafiles... but I do. Meanwhile I migrated to a i7 1st Gen Lappy, and made a clean install of TB and started my email collection all over again... About five years ago, I stopped using the laptop and I stored the HDD... meanwhile I went back to a desktop and this was a i5-4thGen, with YOU GUESSED IT.... a brand new install of TB and a whole new collection of emails in a separate profile... Now... this HDD died... but through SHEER DUMB LUCK, it died DURING a back up of the drive... what was the dumb luck... the drive it was backing up to was considerably larger, and the death occurred in the zone between the partitions... having stretched the original backup of the old c_drive I didn't lose any of the d_drive 2nd partition.... ANYWAY... just pure dumb luck... I have a complete profile... so on my new i5-4670, I've imported the previous profile... but I've still not found out HOW TO merge my old inboxes of the same email addresses from the previous datasets. Can anyone help me please?