there isnt really a solution for this problem right now if you want to contact this person in the Steemitspace.
I predict "private" messaging between steemit users will be an available tool after Beta state.
But of course there are external tools you could use.
for example
https://steemit.chat/home
https://steem.slack.com/
or you could ask for the emailadress.
for now you unfortunately have to manage it with this.
Well, I wouldn't give my e-mail-adress here. There's a lot of freaks, you know. But thanks for the tipps :)
you can get a new one !?
No, one person can only have one e-mail-adress!!!