Merge email addresses?

Hi, I'm just about to set up my laptop with Office (2013) for my aunt. I would like to sign up for Outlook with an @ web.de email, but that does not work.

With the in Win10 preinstalled Mail App everything goes super! Now I've thought about creating a new email for you, but to make sure that all emails from the old @ web.de email address automatically come into the new. How does it work?

You can set up a permanent forwarding: https://hilfe.web.de/email/einstellungen/weiterleitung-einrichten.html