Notes/Domino 6 and 7 Forum : Verify that local domain recipients...

I've read through ALL the posts on the subject - but I'm still curious as to how people feel about this setting (below) and it's bearing on dead mail & spam in general?

Can some individuals who have had this established / in place for some time comment?

Thanks!

C>

Verify that local domain recipients exist in the Domino Directory Specifies whether the SMTP listener checks recipient names specified in RCPT TO commands against entries in the Domino Directory
Choose one:
Enabled - If the domain part an address specified in an SMTP RCPT TO command matches one of the configured local Internet domains, the SMTP listener checks all configured directories to determine whether the specified recipient is a valid user. If all lookups complete successfully and no matching username is found, the SMTP server returns a 550 permanent failure response indicating that the user is unknown. For example:
550 bad_user@yourdomain.com ... No such user
Choosing this setting can help prevent messages sent to nonexistent users (for example, spam messages and messages intended for users who have left the organization) from accumulating in MAIL.BOX as dead mail.
To avoid messages from being rejected as a result of directory unavailability, Domino accepts messages when an attempted directory lookup does not complete successfully.
To avoid unnecessary directory lookups, Domino completes the other SMTP inbound tests configured in the relay, sender, and recipient controls before verifying names in the Domino Directory.
Note When this setting is enabled, the server cannot relay mail to a smart host, because Domino rejects messages addressed to local domain recipients who are not listed in the Domino Directory.
Disabled - (default) The SMTP listener does not check whether local domain recipients specified in the RCPT TO command are listed in the Domino Directory.