The old servers
aqua.rahul.net will no longer accept smtp connections from the outside. So there will be no more incoming mail from the outside.
The intent is to prevent your incoming mailbox on the old servers from having any more new mail in it from the outside. Any server trying to send mail to our old servers will be unable to connect, and will keep mail queued for some time, usually one to three days. Then it will bounce back to the sender.
All domains should have been switched by now to point to the new servers. The only mail arriving for the old servers should have been spam.
Some time between now and the 20th, when everything will be shut down, you may want to check for incoming mail on the old servers, just in case there is anything there that you missed.