This filter now also checks e-mail from our customers and free e-mail providers such as GMX, Google Mail and Hotmail if the e-mail is sent from a Swisscom connection. As a result of the introduction of the new spam filter, e-mail that is sent with SMTP authentication via port 25 can no longer be sent. In such cases, the port setting in the e-mail program must be changed from port 25 to port 587 (standard port for SMTP submission).
More information about your E-Mail settings can be found under Mail Domain FAQ.