[Xastir] Message Failure

[Max Harper]

About half the time I try to send an email to this group I get this failure message. I've also had messages sent that never show up even without the failure. My email address is with Yahoo so I have no control over spam that is sent by others. Am I the only one having this problem?
 
Max KG4PID
 
"Sorry, we were unable to deliver your message to the following address.

<xastir at lists.xastir.org>:
Remote host said: 554 5.7.1 Service unavailable; Client host [98.138.120.56] blocked using dnsbl.sorbs.net; Currently Sending Spam See: http://www.sorbs.net/lookup.shtml?98.138.120.56 [RCPT_TO]"