Package: at Version: 3.1.20-3.1 Severity: minor File: /usr/share/man/man1/at.1.gz
The man page lists i...@rz.uni-karlsruhe.de.
This gives
<i...@rz.uni-karlsruhe.de>: host scc-mailin-cn-01.scc.kit.edu[141.52.226.150]
said: 550 Unrouteable address (in reply to RCPT TO command)
