No reaction from bigstock, but for me problem solved. clicked->forgot password. after this I got mail from bigstock to reset the password. I can login with new password.

Got a response from them, their emails were legit.
Clicking on the link in the second email just leads to the "forgotten email" page anyway. Could have had that easier...

I received an answer too, they are just protecting us.

QuoteWe apologize for the confusion.

This was not a breach to the Bigstock database.

There have been high profile breaches that have been made public recently and we occasionally scan this data programmatically in an effort to protect our users. As a precaution, we have reset passwords on accounts that may or may not have been compromised.

We can confirm that data in your account does not appear to have been changed.

We see that you were able to change your password and login.

Please let us know if you have any additional questions.

Kindest regards,

We also got an answer from bigstock and resetted the passwords.