Since some days there is something wrong with the repo signing key...
Ign:1 http://ftp.de.debian.org/debian stretch InRelease
Hit:2 http://ftp.de.debian.org/debian stretch-updates InRelease
Hit:3 http://security.debian.org stretch/updates InRelease
Hit:4 http://ftp.de.debian.org/debian stretch-backports InRelease
Hit:5 http://ftp.de.debian.org/debian stretch Release
Ign:6 http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0 ./ InRelease
Get:7 http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0 ./ Release [985 B]
Get:8 http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0 ./ Release.gpg [827 B]
Err:8 http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0 ./ Release.gpg
The following signatures were invalid: A21E96611060CF0B4DF11E64A01D0CA80038D0DB
Fetched 1,812 B in 0s (1,816 B/s)
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0 ./ Release: The following signatures were invalid: A21E96611060CF0B4DF11E64A01D0CA80038D0DB
W: Failed to fetch http://obs.kolabsys.com/repositories/Kolab:/16/Debian_9.0/./Release.gpg The following signatures were invalid: A21E96611060CF0B4DF11E64A01D0CA80038D0DB
W: Some index files failed to download. They have been ignored, or old ones used instead.
Is there a new one or did I miss something???
Regards
Darius