Having downloaded the GlogArchive program and run that, I had a csv file. I've sent that to my PC and have removed all lines relating to telephone calls.

Including a header line, I have 2100 lines of data. According to the widget running on the screen of the N900, I should have 2099 so I'd say that's a pretty good match.

Following on from what you said about newline and space, I'm going to try a few lines of data as a test. If that goes well, I'll remove the test messages from the Jolla and then import the lot.