seedcrust

Try mailbrew.com

I had the same issue and this was always enabled

I had the same issue and uninstalled both.

I used to delete manually each container when this happened, through about:preferences container manager, but now there is no more this in Preferences and to remove containers through the Multi-Container extension isn't the best thing.

Tried do that by editing some files too but the hundreds os containers keep reappearing after few days, or on new installations.