You can have a virtual inbox with unified folders. The accounts remain separate, yet appear as one.

Thks David. I tried your description with copilot, yet copilot seems to refer to an outdated Mozilla version. How can I install this virtual inbox please?

Click View>folders and tick 'unified folders'

Hi, don't know if this is the right way, but:

I did as above, I now have unified folders and a Inbox in there. If I click that Inbox nothing is displayed, even though I have two e-mail accounts with their individual inboxes, containing mails. I can see those when I click the inbox of those accounts. Any ideas?

Rightclick on the inbox and properties and then click 'choose' on the properties pane. That should show the accounts. Let me know status.

Hi David, thanks for the advice, I did as you said, selected my two e-mail account folders, hit "Update", but still nothing is shown, except for the header, which says "12 messages", which is correct, because at this point the two account inboxes contain exactly that!