Since wednesday 22 july i get an error message invalid address with id 0x8000CCC79 on a hotmail address with underscore in the name. Tuesday 21 july i could send emails to this same addres without problems. On 21 july windows was update with KB3079904 Security update for windows 7.

I use windows 7 with live mail 2012. I contacted my ISP several times but my settings are correct and everything should work. So they cannot help me.

As a test i tried to enter a email address in outlook with underscores in the name and i get an error message that only letters, digits , . - and _ are allowed. Since i use _ this is an incorrect error message.

I also tried an new email account in livemail with underscore, and sending an email to this address also results in error message 0x8CCC79.

Can somebody tell me what is / went wrong and how to repair?