No Incoming mail as well as not able to migrate mails

No Incoming mail as well as not able to migrate mails

  1. Outgoing mails are working fine. But the replies to same mail is not reaching.
  2. I followed allowed steps of migration. Then after when I click on start it says "Add accounts before starting migration" I have already two accounts same as those in previous server. Then what is the issue here?

Please reply asap