* * * * *
                                        
                         Sendmail Blows, and here's why
                                        
My my my … it looks like sendmail [1] might be the culprit here, not
Exchange. [2] As per RFC-821: [3]

> 
>       "User name" is a fuzzy term and used purposely.  If a host
>       implements the VRFY or EXPN commands then at least local mailboxes
>       must be recognized as "user names".  If a host chooses to
>       recognize other strings as "user names" that is allowed.
> 
>       In some hosts the distinction between a mailing list and an alias
>       for a single mailbox is a bit fuzzy, since a common data structure
>       may hold both types of entries, and it is possible to have mailing
>       lists of one mailbox.  If a request is made to verify a mailing
>       list a positive response can be given if on receipt of a message
>       so addressed it will be delivered to everyone on the list,
>       otherwise an error should be reported (e.g., "550 That is a
>       mailing list, not a user").  If a request is made to expand a user
>       name a positive response can be formed by returning a list
>       containing one name, or an error can be reported (e.g., "550 That
>       is a user name, not a mailing list").
> 
> 
> RFC-821, § 3.3. VERIFYING AND EXPANDING
> 

> 
>          EXPAND (EXPN)
> 
>             This command asks the receiver to confirm that the argument
>             identifies a mailing list, and if so, to return the
>             membership of that list.  The full name of the users (if
>             known) and the fully specified mailboxes are returned in a
>             multiline reply.
> 
>             This command has no effect on any of the reverse-path
>             buffer, the forward-path buffer, or the mail data buffer.
> 
> 
> RFC-821, § 4.1.1. COMMAND SEMANTICS
> 

From my reading, it seems that sendmail should not be sending back the
program name, but rather, it should just return the email address passed in.

This is not good …

[1] http://www.sendmail.org/
[2] gopher://gopher.conman.org/0Phlog:2000/08/22.3
[3] ftp://nis.nsf.net/document/rfc/rfc0821.txt

Email author at sean@conman.org

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