I'm trying to do a task assignment with my SharePoint site and Nintex (I did it today on Flow too)
I have a SharePoint site with two SharePoint Account but no email address with them
So I have to use a @gmail.com address but I received nothing, I make a trial with the option send a mail, and I received well the message in my mailbox,
So is it possible that my assignment doesn’t work as I’m not using mail from my organization? (For Flow is not a problem as I have an interface on the flow site)
Assignee should be inside your domain. You cannot assign the task to user who is outside your domain. Sending email does not have issue. Assigning task will create the task and assign to that user, so the user should have SharePoint profile.
I think Flow is different. Flow might have some service connection between Flow and SharePoint. I haven't tried Flow yet until now.
You can eventually try to create a guest account for you "gmail" account in AAD, then assign a task to that account.
Possibly you can also try with Nintex Workflow Cloud - but haven't checked if there you can assign a task to a person from outside of your tenant.