The following message to <praesident(a)hs-hannover.de&gt; was undeliverable. The reason for the problem: 5.1.0 - Unknown address error 550-'5.7.1 <praesident(a)hs-hannover.de&gt;: Recipient address rejected: Please see http://www.openspf.org/Why?s=mfrom;id=stapf%40zapf.in;ip=129.206.119.212;... Dieser Server arbeitet gerne an der Hochschule Hannover.'