Five K and YVN will never ask for your login information via email.

If you receive emails requesting your username and password for any online service, you can be sure that it is a Phishing Attempt (Wikipedia).

Follow this guide when dealing with personal information on the Web: antiphishing.org

Five K and YVN will never send you emails with attachments
If you receive emails asking you to run an attachment to "Fix" your account settings, you can be sure that this is some form of malware. - Do not open it.