The procedure will vary depending on which email account you have, but most of the popular sites have similar options. If you want to block someone from your email, say for example you want to block someone from your Yahoo mail, there are a couple of things you can do. Firstly, log in to you email account then click on mail options- choose 'block email addresses'- then enter the person email address. Yahoo allows 500 blocks per free account.
You can also go to an email that user has sent you, next click the option that says 'SPAM'. This should probably do the trick. Alternatively, go to the options, choose the option that says 'create a filter' and select that person email address- this way whenever this person sends you an email it will directly go to trash instead of to your inbox.
You can also go to an email that user has sent you, next click the option that says 'SPAM'. This should probably do the trick. Alternatively, go to the options, choose the option that says 'create a filter' and select that person email address- this way whenever this person sends you an email it will directly go to trash instead of to your inbox.