running Delta Chat 0.510.1 I just had it happen that one of the devices sent messages unencrypted to the other device (both devices are setup for different E-Mail-accounts). It kept sending unencrypted messages until I replied from the other device. That reply was correctly send encrypted. Since then the other device, that was previously sending unencrypted, returned to sending encrypted.
A) I wonder how that could happen!
B) That must under all circumstances never ever happen if Delta Chat is used in critical environments!
Feel free to comment and maybe tell me if I could be of any help to find out where the error lies.