MailScanner & CentOS5/Sendmail

Greg Matthews gmatt at
Fri May 16 12:08:24 IST 2008

David Lee wrote:
> Another method available is sendmail's 'virtusertable' which gives:
>    user at -> id-A at machine-Z
>    user at -> id-B at machine-Y
>    a.n.other at -> id-C at machineX
> And (the bit you probably want to know) if the recipient is not in the
> left-hand-side of the table then the email is rejected at SMTP stage.
> (There are many other details, but this MailScanner-list discussion is
> already approaching "off-topic"!)
> This 'virtusertable' facility can be useful at large sites with multiple
> domains. Our two main domains each have around 25,000 entries.
> So we use:
>  o  'virtusertable': accept email for known users, reject unknown users
>     (with frequent, automated updates from Personnel (HR) databases);
>  o  'access': occasional blocking of external things that are bothering
>     us (updates relatively infrequent; done by Postmaster).

additionally, we also make use of milter-ahead as we cannot always be 
authoritative for users at domains which we relay for. Using this milter 
allows us to delegate that authority to the domains themselves


Greg Matthews           01491 692445
Head of UNIX/Linux, iTSS Wallingford

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