[amsat-bb] email blocked

[wa4hfn at comcast.net]

I have been unable to receive any email from the amsat bb. I found this 

Delivery to the following recipient failed permanently:

      amsat-bb at amsat.com

 Technical details of permanent failure:
 Google tried to deliver your message, but it was rejected by the server for the recipient domain amsat.com by mx2.daemonmail.net. [216.104.161.5].

 The error that the other server returned was:
 554 5.7.1 <amsat-bb at amsat.com>: Relay access denied

 Why has amsat blocked me?  I have done nothing to cause this . This is the second time this has happened, is it a glich or is someone doing it

WA4HFN   Damon em55
www.starcommgroup.org