I've searched the internet to no avail. Using my contacts list in gmail I have one address in red. When it is included in a group message the message is knocked back. The recipients former address was marked in red and the same problem arose. That is why I got a new address from him. I am using windows 7 which is not supported now. Could that be anything to do with it? And how do I fix the problem?

maybe go back to windows 95 ? 

3 hours ago, Gandtee said:

Could that be anything to do with it?

No. if you are using a web browser to access gmail it won't have anything to do with the operating system. 

As it is only the one address that is affected it sounds like an issue with that address - is it another gmail address?

11 hours ago, topt said:

No. if you are using a web browser to access gmail it won't have anything to do with the operating system. 

As it is only the one address that is affected it sounds like an issue with that address - is it another gmail address?

Both loxinfo addresses to the same recipient.