Thank you YadaYadaYada and Kamran.

- I have removed all plugins and cleared cache and cookies on firefox, I tried reinstalling it and using it in safe mode
- I have disabled the Mac firewall
- I have run antivirus scans and malware scans, I did not find any malware
- I have updated java to the latest version
- I have tried logging in on Firefox, Safari, Chrome

None of these worked.

I have the same problem on
- Imac (OS 10.12.1)
- Notebook (Win 10)
- Tablet (Android)
- Old notebook (Ubuntu)

The website works on an old macbook where I was already logged in weeks ago.

I tested the reCHAPTA on this link and it�s not working, I suppose that is the issue
https://patrickhlauke.github.io/recaptcha/

How do I fix the reCHAPTA?

I can't login to shutterstock anymore because I can't see the rechapta code on the login window, it's just blank. I tried on Firefox, Safari and Chrome and still I have the same problem. I found an article by shutterstock where they say that could be a malware or a trojan virus, did someone experience this? Any help please?

Thank you!

I have received the same mail too and I definitely do not have spammy titles.
Here they give some explanations and examples:

http://www.shutterstock.com/contributorsupport/articles/kbat02/000010523