It's also worth noting that verification is much easier these days given that cross-signing has been implemented.
Before you had to verify each pair of (sender, recipient) devices. This meant N*M verifications.
Now you only need to verify a new device when you are setting it up and each new recipient when you start talking to them for the first time. So it's N+M verifications.
Before you had to verify each pair of (sender, recipient) devices. This meant N*M verifications.
Now you only need to verify a new device when you are setting it up and each new recipient when you start talking to them for the first time. So it's N+M verifications.