want to block some unwanted emails in gmail ?

JUST follow these steps
1. Login to your account
2. At the top-right corner, click on Settings
3. Under Settings, click on Filters
4. You’ll now see an option “Create a new filter“, click on it
5. Now in the Form field enter the email address from which you do not want to receive emails
For ex. you may enter abc@xyz.com in the From field to block all incoming emails from this address. However if you want to block the whole domain then use the following syntax: *@xyz.com. Now all the incoming emails from the domain xyz.com will be blocked.
6. Click on Next Step, select the action you’d like to take on the blocked emails. You may select the option Delete it so that the blocked email is moved to trash. To unblock the email, all you need to do is just delete the filter that you’ve created.