The removal came after users widely shared a blog from Texts.com showing that messages sent with Sunbird’s system aren’t actually end-to-end encrypted — and that it’s not hard to compromise it.

End to end encryption means my device encrypts it and yours decrypts it. Their bridge will never be able to support this, it has to decrypt it in the middle to transfer to and from the other service. At the very best, when their implementation isn’t slipshod, you have to trust them when they say they ignore all the (hopefully temporary) plain text data that is passing through their bridge.