server name in updates email

Hi. How can I change the server name in the email message that I receive when there are updates available. This is an example of message that I receive:

An update to krb5-locales from 1.13.2+dfsg-5 to 1.13.2+dfsg-5ubuntu1 is available. An update to libgssapi-krb5-2 from 1.13.2+dfsg-5 to 1.13.2+dfsg-5ubuntu1 is available. An update to libk5crypto3 from 1.13.2+dfsg-5 to 1.13.2+dfsg-5ubuntu1 is available. An update to libkrb5-3 from 1.13.2+dfsg-5 to 1.13.2+dfsg-5ubuntu1 is available. An update to libkrb5support0 from 1.13.2+dfsg-5 to 1.13.2+dfsg-5ubuntu1 is available.

Updates can be installed at https://cloud01:10000/package-updates/

where do I change "cloud01" to the real server name "cloud01.domain.tld" ?

thanks

Michel.