The following message to <kai.grossjohann@gmx.net> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-"5.7.1 {mx069} The recipient does not accept mails from 'iro.umontreal.ca' over foreign mailservers.\n5.7.1 According to the domain's SPF record your host '206.248.154.182' is not a designated sender.\n5.7.1 ( http://portal.gmx.net/serverrules )"