According to Z8Games "Top 10 FAQs"
How to change my E-mail
You can change this information by sending your account ID, security question / security answer to Z8Games - Support
4. I forgot the answer to my security question.
The only way to retrieve the answer to your security question is to submit a support ticket containing all the information you entered during the registration process, in addition to your registered email address. This is in order to verify your identity. Be warned, the process of retrieving the answer to your security question can take time.
As far as I can tell the E-Mail and Security Question is tied together this is put in place to prevent Scamming accounts. If there were a way to change the E-mail without a Security Question you could easily steal accounts that you know the ID and password to.
The first choice is to try to remember E-mails you've used in the past And go to the "Lost Login ID / Password" Section of the Z8games website.
Your only other choice is to contact Z8Games - Support
When contacting them mention your situation
Give them your Login ID and Any information you do remember.
Provide your IP Address
What Is My IP Address - Shows Your IP Address
And the last 4 digits of your Credit card number only if you bought ZP from Z8games
They will verify and check everything so please don't be trying to steal an account!
If this is your account and you can provide enough details they will reset your information or change it for you. It's very difficult to get requests like these done to prevent stealing. Good luck!
I do not know if there are "password stealers" and all of that available, but if they are we do not support them on MPGH as you could easily use them on other members!
Next time post in the help section
CrossFire Help - MPGH - MultiPlayer Game Hacking