Are Signal Messenger's servers able to see who I'm talking to?
I'm aware of Signal's "no log policy", but I'm wondering if such information is visible to the servers at all. I'm assuming "Sealed sender" is what is supposed to protect this information? If so, how effective is it?
This would have to be available. The only way to avoid metadata like this is something like onion routing... Session will do that, probably your best bet if you're worried about this.