rtin: ... illegal character in hostname

[Stef Hoesli Wiederwald <debian@sos.ethz.ch>]

When I reply to an author of an usenet posting using rtin, I get the
following error message from our Mailserver:

|------------------------- Message log follows: -------------------------|
 no valid recipients were found for this message
|------------------------- Failed addresses follow: ---------------------|
 Adrian Sieber \<Adrian.Sieber@unifr.ch\> ... illegal character in hostname
|------------------------- Message text follows: ------------------------|

Whats wrong with rtin?

Stef