Yes, indeed, if you're looking to scale up to handle high concurrent user loads, scaling out horizontally is your best bet. We've got a client right now serving 700+ connections at the moment, and they're on four separate NodeBB instances. It's probably too much for what they need, but it's always nice to have more capacity than needed in case of spikes, etc.
Transitioning to NodeBB from legacy mailing list (Mailman)
We are considering NodeBB as a replacement to our project mailing lists that are currently hosted by Mailman (also on Nabble).
Is there a way to have a setup where messages sent to the mailing list would be also synchronized to the NodeBB forum? This would help us evaluate both in parallel, and support communities of users who prefer traditional mailing list.
Does anyone has experience migrating legacy mailing list content to NodeBB? I know there are some forum migration plugins, but I did not see ones specifically for legacy mailing lists.
Nothing like that unfortunately. But we do have an email responder plugin - you get an email on a new reply, and then you can reply directly to the email and it gets posted.