If you block a Gmail contacts it will prevent the person from talking to you and seeing you when you are signed in to Gmail or Google Talk. It’s quite easy to block any contacts at any point of time and generally I used a lot time when a contact is disturbing me a lot. In general this is the way you get into invisible mode in GMail or Gtalk but how many friends you will block if that is the case so in this cases where I like to go invisible to users I like Yahoo services and I think that’s the only reason I like them. Back to GMail, if you want to go Offline to a contact then there is only one procedure i.e. block him, sounds risky but that’s only the final decision you can do.
How to Unblock a Gmail or GTalk Contacts
The process of unblocking a person is just similar to blocking an ID. Just like you block a person, select the same option to unblock it.

These type of article would be more useful to block or unblock g mail contacts. Thanks a lot for given your post on here 🙂
Thanks for the post. I was not knowing how to do this till date 😛