lots of phishing from .bc.googleusercontent.com

You can use pandora.sic.tu-dortmund.de to check whether emails came from there.
Phishing from there, which simulate account blocking, waiting documents etc., PLEASE DELETE or report with the Outlook plugin.
Examples:
SUBJECT: EMAIL ACCOUNT SHUT DOWN REQUEST FOR ihr.name@tu-dortmund.de ACTIVATED
SUBJECT: TU Dortmund University Mailbox Update
SUBJECT: [ihr.name@tu-dortmund.de]: Please confirm three (3) Pending Messages.
and many more.
Please note the information on spam in the service portal.