This is not possible.
User can send a mail from Gmail account to other ones. Hotmail and Yahoo are examples of those. Gmail provides cross server mailing too.
To Check gmail, go to gmail.com and type in your user name and your password.
You can unblock a Gmail user by removing the filters. Filters are the ones that block somebody. Removing filter will reverse the effect.
Open the email you have received from the GMail user and click on the "Report Spam" button.
Yes, that is possible.
No Email ID is a verification for Gmail. It is used to verify if a user is a part of Gmail or not. The password and the ID form a unique combination.
Yes, Gmail is a user friendly email service. It is a type of service that an amateur can also operate on. It is simple to use and is very fast.
7000mb may be
You can recover your username also from Gmail. It is the same way you can recover your password. Some steps are to be followed for that.
yes it is possible beacouse in the gmail database there are in no record of that user
Gmail itself is a portal for logging in. It contains the database of google ID's and passwords. A user can log himself into using the right credentials.
You can remove the unnecessary data to avoid Gmail being full. Gmail offers 15 GB of data per user. You can always use that for mails only not attachments.