I have a problem sending emails to .coop domains. I try to use both webmail and Thunderbird (imap) systems to send an email to domain @coop57.coop. When I try it I recive this code error:

xxxxx @coop57.coop  Error, ERROR_CODE :550, ERROR_CODE :74.201.84.155 is not allowed to send mail from lemaxcooperativa.com. Please see  http://www.openspf.net/Why?scope=mfrom;identity=silvia.magdaleno@lemaxcooperativa.com;ip=74.201.84.155  
xxxxx@coop57.coop  Error, ERROR_CODE :550, ERROR_CODE :74.201.84.155 is not allowed to send mail from lemaxcooperativa.com. Please see  http://www.openspf.net/Why?scope=mfrom;identity=silvia.magdaleno@lemaxcooperativa.com;ip=74.201.84.155  

What can I do to send to this domain? You need to add something on your mail server?

Thanks,

David.