To allow incomming mail to exceed users diskquota install the
follwing program with EXQUOTA priv:

  local VMS mail (VT interface)         SYS$SYSTEM:MAIL.EXE
  local VMS mail (X interface)          SYS$SYSTEM:DECW$MAIL.EXE
  remote VMS mail                       SYS$SYSTEM:MAIL_SERVER.EXE
  remote PCSA mail                      SYS$SYSTEM:PCSA$MAIL_SERVER.EXE

See also mail-images.