I was wondering if there is a way to add external users to SharePoint Online. The external users are nothing but people who don’t have user accounts in the SharePoint Online environment. The access to external users can be provided by sending them an invitation through e-mail. I’ve learnt that we can send the e-mail invitation to any type of e-mail address such as *.gmail.com, *.yahoo.com or *.yourowndomain.com. However to log-in to the SharePoint online environment, the e-mail account has to be associated with a valid Microsoft account.
Now the a email invite will be sent to the invitees (external users)
Open the e-mail invite and click the link on that.
To accept the invite, you need to have a valid Microsoft account.
This completes the sign-in process for the external user to the SharePoint Online Team site using a valid Microsoft account.