As alumna or alumnus you can find your mails here: https://mailbox.alumni.tu-berlin.de
As exchange user you can access your mails here: https://exchange.tu-berlin.de/owa/
Be aware if you are a member of Technische Universität Berlin (TUB) and get an email which asks for personal information such as tubIT account name and password, or links to a website which asks for these data. Don't answer it. Don't follow the hyperlinks. Never! These emails neither come from tubIT nor from TUB, even if they try to give this impression.
Members of tubIT never ask for your password. Therefore you should never tell or send it to anybody!
This warning is permanently valid, no matter how authentic these emails look like.