I have received a text message that will not open. The icon next to it in my Inbox is a question mark (?) and not the usual little envelope. Can anyone explain or tell me how to open it. I do not recognise the telephone number that sent it ( it is a normal looking UK no,) but this is the 3rd time this has happened and the other two times I did know the number sending the message ,and was expecting a message, but still couldnt open them. Eventually I deleted them.