88  Mail  tralia,  Britain,  France,  and  all  over  the  U.S.  I  speculate  that  the  list  has  at  least  200  recipients,  and  about  25%  of  them  are  actually  UUCP  sites  that  are  MX’d  on  the  Internet.  I  destroyed  about  4,000  copies  of  the  error  message  in  our  queues  here  at  Apple  Computer.  After  I  turned  off  our  SMTP  daemon,  our  secondary  MX  sites  got  whacked.  We  have  a  secondary  MX  site  so  that  when  we’re  down,  someone  else  will  collect  our  mail  in  one  place,  and  deliver  it  to  us  in  an  orderly  fashion,  rather  than  have  every  host  which  has  a  message  for  us  jump  on  us  the  very  second  that  we  come  back  up.  Our  secondary  MX  is  the  CSNET  Relay  (relay.cs.net  and  relay2.cs.net).  They  eventually  destroyed  over  11,000  copies  of  the  error  message  in  the  queues  on  the  two  relay  machines.  Their  post-  mistress  was  at  wit’s  end  when  I  spoke  to  her.  She  wanted  to  know  what  had  hit  her  machines.  It  seems  that  for  every  one  machine  that  had  successfully  contacted  apple.com  and  delivered  a  copy  of  that  error  message,  there  were  three  hosts  which  couldn’t  get  ahold  of  apple.com  because  we  were  overloaded  from  all  the  mail,  and  so  they  contacted  the  CSNET  Relay  instead.  I  also  heard  from  CSNET  that  UUNET,  a  major  MX  site  for  many  other  hosts,  had  destroyed  2,000  copies  of  the  error  message.  I  pre-  sume  that  their  modems  were  very  busy  delivering  copies  of  the  error  message  from  outlying  UUCP  sites  back  to  us  at  Apple  Computer.  This  instantiation  of  this  problem  has  abated  for  the  moment,  but  I’m  still  spending  a  lot  of  time  answering  e-mail  queries  from  postmas-  ters  all  over  the  world.  The  next  day,  I  replaced  the  current  release  of  MAIL*LINK  SMTP  with  a  beta  test  version  of  their  next  release.  It  has  not  shown  the  header  mangling  bug,  yet.  The  final  chapter  of  this  horror  story  has  yet  to  be  written.  The  versions  of  sendmail  with  this  behavior  are  still  out  there  on  hun-  dreds  of  thousands  of  computers,  waiting  for  another  chance  to  bury  some  unlucky  site  in  error  messages.  
Apple  Computer’s  Mail  Disaster  of  1991  89  Are  you  next?  [insert  theme  from  “The  Twilight  Zone”]  just  the  vax,  ma’am,  Erik  E.  Fair  fair@apple.com  
            
            






































































































































































































































































































































































