I have seen the same with personal  mail on LEPICS. My guess is that this
is a bug in EXECIO PUNCH, or quite possibly CARDPH: UR devices were fully
synchronous under  SP, so that a  SIO held the virtual  machine until the
I/O completed,  but they are more  asynchronous under XA, and  it becomes
important to  wait for  the CE  before filling the  buffer with  the next
card. Try running LISTSERV under CMS 5.x.
 
  Eric