It means sendmail is finding it difficult to deliver your mail. Try printing out a "good" e-mail to a text file (or use the dead.letter you found, though you might have to edit it a bit), and pipe it through sendmail yourself: 
$ sendmail -t <message

[download]
See if sendmail says anything to you.

In reply to Re: Re: Re: Ways to test sendmail by Fastolfe
in thread Ways to test sendmail by belize

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