"Runescape Account Validation - Notice" Is it legit?

Here's the full message you submitted, so we're starting in the same place:

This is a automated message from Jagex entertainment.

We have information regarding you attemping to buy or sell your Runescape account.
This is against the Terms of Use you agreed to when you created your account.

In order to validate the correct owner is still in control of the account please fill out the form below and reply back to this e-mail.

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Username:
Password:
Recovery Question Answer 1:
Recovery Question Answer 2:
Recovery Question Answer 3:
Recovery Question Answer 4:
Recovery Question Answer 5:
First ever password used on the account:
Another password used on the account:
When was the account created:
What internet service provider was used when the account was made:
Any other details which might help us confirm the proper ownership:

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Please respond as soon as possible to this e-mail otherwise we will assume account is in another owners control and take action.

Thanks for your time,
Marcus.
Customer support team.
Jagex entertainment.

Further, a quick glance reveals that the return email address is "Runescape Authentication "

Let's think about this. Jagex is a big company and clearly has a lot of computers and their own domain names, etc. Why would they use an email address off Google's Gmail service? Why? Because it's a social engineering / phishing scam.

That's right, this is not a legitimate email message and you should not respond to it at all.

How did I know when I got this message? Two clues: the Gmail return address and the fact that I don't actually have a Runescape account.

Ooops. :-)

Suffice to say, always always be suspicious of any email like this and never click on a link included or email anyone your account credentials.

Be careful out there!