Google Translation:

UPC Webmail

Dear Users!

We would like to draw your attention to the fact that the technical support for UPC Webmail and the related e-mail service will be discontinued by the service provider on March 1 , 2021.
Please whom to @ upcmail.hu, @ chello.hu, @ monornet.hu, @upctelekom.hu, @ upc.hu or @ vodamail.hu ending address is specified, replace, because of using a non-functioning e-mail address, it may result in the risk of permanent loss of your user account at a later date.

You can check the currently entered e-mail addresses in the [Profile] menu.
If necessary, >> HERE << ask for help.