"Events and Tasks" relate to the Lightning calendar. So any export and import options on that menu would be in connection with the calendar. I see no reason to suppose they would be of any help with email messages.

The advice I gave in the other thread stands.

What do you want to export, and for what purpose? To shift to another Thunderbird, moving your profile over is the most straightforward approach.

If you want to import your messages into another email client then first of all I'd look at whether it needs to be done; IMAP makes importing and exporting largely unnecessary. If you do want to export messages, then again the ImportExportTools add-on could be useful, though of course success depends on whether the importing email client can use eml files.

If you're just backing up as a precaution against hardware failure then again, copying your profile is again the most suitable strategy.

Google Translate gives "Events and tasks" for "Gebeurtenissen en taken" which is a perfect match to the English version.

Hello,

The menu is called Events and Tasks in English allright (as mentioned in the other question), and the Export… item should open a Select Calendar dialog (Dutch: Agenda selecteren) offering you to select one of the available calendars to export from, provided that you have any.

Is your intention to export Calendar data anyway? If so,

• Are you sure your Lightning version is up to date?
• Can you try disabling all add-ons except for Lightning (since Safe Mode would disable all of them) and see if the problem persists? If it doesn’t, re-enable your add-ons one by one afterwards until you found the add-on possibly responsible for the issue.

Sumo article about exporting calendars

Note that the Events and Tasks menu item is not intended for exporting other things than Calendar related items - in fact, if you disable or uninstall Lightning, the Events and Tasks menu isn’t even available.

If your intention is to export email addresses however, open the Address book and choose Export… from the Tools menu (Extra in Dutch).

If your intention is to export messages however, you can install the ImportExportTools add-on from AMO, or in this case (since the most recent version isn’t listed there), from the link at the bottom of the ImportExportTools page.

And if your intention is to export/transfer emails to another PC, have a look at the Moving Thunderbird data to a new computer article, as well as the article about profiles it refers to.

A little advise: please avoid using MozBackup for any copy/paste tasks related to Thunderbird and Firefox (backups), since it’s no longer supported and may cause data loss due to changed file structures and their purposes.