Hybrid deployment in Office 365 | Checklist and pre requirements

Dear Avisek,

if you want Hybrid then your Anywhere, EWS and Autodiscover URL's should be available publicly and published in your exchange servers because autodiscover service will do the autodicsovery of mailboxes either user's mailbox in the cloud or on-premises and EWS will give you the advantage of organization relationships with exchange online organization for unified GAL, calendar and free/busy information sharing and if your exchange do not have EWS Public names published on your exchaneg then your Hybrid Wizard will be failed saying :Organization relationships failed......." because it need to make a trust relationship with your exchange and MFG (Microsoft ForeFront Gateway) for free/busy and calendar sharing.

if your OWA not published it will not gives your users access to Exchange online URL access as a scilent redirection but each users need to open Exchange online URL i.s. https://mail.office365.com and for every user migrated to cloud you need to tell that now your mailbox is in the cloud and you need to use https://mail.office365.com as OWA address and this will not be seamless transaction for your users.

i hope this answer your queries and do let me know if you need further help from my end.