Mail log problem -

Mike Wright xktnniuymlla at
Thu Jun 28 21:34:58 UTC 2007

<snip />
> The maillog does show some cryptic [to me] errors:
> Jun 28 16:36:55 box6 sendmail[1091]: l5SKaLF4001091: 
> to=bobgoodwin at, ctladdr=root (0/0), delay=00:00:34, 
> xdelay=00:00:30, mailer=relay, pri=989592, relay=[] 
> [], dsn=5.6.0, stat=Data format error
> Jun 28 16:36:55 box6 sendmail[1091]: l5SKaLF4001091: l5SKaLF5001091: 
> DSN: Data format error
> Perhaps someone can tell me what this means?

DSN = delivery status notification

Found this on google:

if your sending machine does not have it's own name/IPaddress in
its /etc/hosts file, it will cause the upstream target/relay host
to reject the message with something which means: "I don't know who
you are". The sending MTA sendmail then issues the error in the
maillog "...dsn=5.6.0 stat=Data Format Error". The fix for this is
to have a correct /etc/hosts;

The advice to fix your dns seems to be spot on.


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