Cannot sent Email to Mindsring,com

I get the following message & do not know how to fix it

“Unable to deliver the message due to a communications failure
The MTS-ID of the original message is: c=US;a= ;p=RELIANCE STEEL ?;l=TUBING-010308165032Z-6560
MSEXCH:IMS:RELIANCE STEEL & ALUMINUM CO.:RELIANCE:TUBING 3550 (000B099C) 550 telephone number listed in your documentation.”