I won't write much.
Someone is collecting emails and steem account names of their owners. Probably for advertisement and spam sending purposes. However it may be the first step of phishing attack.
Next in a few weeks, you will get an email with request of using your login credentials on some page like "steeemit.com" or "steemiit.com" (url with one changed letter) standard practices, you won't spot difference and you will login on attacker page giving him everything he need.
Why it is so dangerous?
Steemit.com has got open source code, so anybody can in a few minutes put online a copy of steemit, change one line of code and steal everything from you.
Have a nice day :)