Cindy:

I suggest bucking it to [log in to unmask] for further explanation.
But in the mean time, DON'T PANIC!!!! ;-) sometimes these things are very
temporary conditions especially if the original error occurred on weekends,
after working hours, or mid-nite (recipient's time zone).  (This error does
NOT contain any timestamp, so you could wait a couple of days and see if it
is still occurring.)

What  has this address done?  Copy of error message follows:
<<<<<<<<<<<<<<

Err First Last  Address
--- ----- ----- -------
  1 10/22 10/22 Jacque Jones <[log in to unmask]>
                Last error: Mailer sparticus.EUREKANET.COM said: "551
                            <[log in to unmask]>... we do not relay"