The short answer is: "No".
If you have access to FirstAgenda in an AD-organisation then you use your AD-mail to log in. However, if you afterwards get invited to a different oranisation - e.g. a board then you might receive the invitation in your AD-mail, but you can not use your AD-mail as username. This is because the AD-mail is "reserved" for your AD-organisation. Therefore, you have to set up a username for a different email address - e.g. by using Gmail.
In the future you will therefore have two different logins (= two different users) to FirstAgenda:
- Your AD-login (AD-mail) when you log in to your AD-organisation
- Your FirstAgenda-login when you log in to other organisations (boards in the example above)