Hi 

You can do it from below Microsoft recommended  third party migration partners
1) Quest Coexistence Manager.

2) Full Armor

3) Binary Tree Co-Existence

4) CASAHL Technology

I have written an overview of coexistence manager which you can go through

http://exchangequery.com/2014/09/12/readiness-to-migrate-lotus-notes-to-office-365-with-quest-co-existence-manager/

hi, 

Already I have Lotus mail server. Now i want to migrate exchange 2013. but client mail user 500+ and their didn't give downtime for migration purpose. Did have any systems to migrate lotus to exchange without downtime. If have pls give me suggestion step by step as soon.

Sorry for my En