Add/register external users to our office 365 without having to invite them inadvance to access a site collection

Question

Usually when i share a site with external users, i do the following steps:-

1. Enable external sharing on the related site collection.

2. I add/share the external users email addresses to a site collection's group (ie members group).

3. Then the external users will receive an email, and once the external user login to sharepoint, his/her email address will be added a Guest account inside office 365, and will have this format user.name_ourpartner.net#EXT#@SPTenant.com.

but now i am facing this scenario:-

1. we have sharepoint enterprise on-premises 2013. and we have 10 external users' accounts added to our on-premises active directory (those represents a partner company which have separate domain), and those external users were accessing the the on-premises sharepoint sites using VPN.

2. now i am using a third party tool named sharegate, to migrate the on-premises site collections to sharepoint online.

But i want to map the on-premises external users to new external users (Guests) accounts. and to be able to do the mapping i have to add the external users in-advance to office 365 . so i am not sure if i can replicate the above 3 steps manually ?.. in other, words; can i without sending the external users invitation emails , to have their accounts added inside office 365 as external users (Guest)?

Answer 1

Based on my knowledge, user can't be add in office 365 without invitation. Even though if you are adding as new guest user in Azure Active Directory, User will get an invitation email and he need to accept it for create a new password and for email ID verification

I hope the mentioned external users were created as a contact in On-Premises Active Directory, so i suggest you to use the Azure Active Directory connect (Download Here) to synchronize all the on-premises users to Azure Active Directory