Email Security Gateway models 300 and above, all versions of firmware
If you are not using LDAP verification for all of your domains and you have per-user quarantine boxes enabled, quarantined mail addressed to nonexistent recipients may be stored in quarantine mailboxes for these nonexistent users on the Email Security Gateway. A feature exists to help you purge these invalid accounts, provided your mail server uses some form of recipient verification.
The Remove All Invalid Accounts button appears at the bottom of the Users > Account View page. If you are using LDAP for your recipient verification, it will only work on the domains for which it has been configured (under the Domains tab). If a given domain is not using LDAP and has no other form of recipient verification, the Remove All Invalid Acounts button cannot work.
If you are using SMTP verification, trying to send an email message to an invalid user on your mail server should look something like this:
telnet mailserver.yourdomain.com 25
Connected to mailserver.yourdomain.com (22.214.171.124).
Escape character is '^]'.
220 THE 220 BANNER
550 User does not exist
The Email Security Gateway will connect to your mail server and check each address in this fashion, should LDAP verification be unavailable. The 550 message following the rcpt to command indicates to the Barracuda that the current email address is invalid. The Barracuda will use the destination server information for each domain under the Domains tab, so a misconfiguration there could prevent the Remove All Invalid Accounts button from working. Be sure you haven't entered the address or hostname of the mail server itself (as oppose to your domain) while also enabling the Use MX Records option!
Unfortunately, if you are not using either LDAP or SMTP recipient verification, the Remove All Invalid Accounts button will be unable to tell valid and invalid accounts apart.
In firmware versions 3.5.11 and above, a third method of recipient verification is available - the local Valid Recipients list. This feature is compatible with the Remove All Invalid Accounts button as well. For information on how the different methods of recipient verification interact with one another, see Solution #00003521.
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