It means that now gmail has a dead post office type thing where all the emails which are not delivered and later on these are processed by postmaster@nic(dot)co(dot)in and sent to correct addresses. Moreover it even sent an advisory to the originator that you have sent email to a wrong address and Postmaster did its action by sending it to correct id.
Verdict
This is a good advancement but if Postmaster sends the email to a wrong email id. May be they may have some checks and balances to rule it out.