Sendmail and backup MX

[Scott Silva]

John Rudd spake the following on 9/26/2005 2:37 PM:
> On Sep 26, 2005, at 12:13, Scott Silva wrote:
> 
>> Not a MailScanner issue, but ...
>> Does anybody have any simple solutions for sendmail that only lets the
>> backup MX accept mail when the primary is down?
>> I don't want to re-invent the wheel if someone already has a working
>> solution.
>>
> 
> Get mimedefang.  Run it on your backup.  www.mimedefang.org
> 
> 
> There's a function it has called "filter_recipient" which you have to
> write (in /etc/mail/mimedefang-filter), and which you have to turn on in
> the startup script.  Here's what I would suggest:
> 
> 
> sub filter_recipient {
>    my ($recip, $sender, $ip, $host, $first, $helo, $rcpt_mailer,
>        $rcpt_host, $rcpt_addr) = @_;
>    my ($type, $msg);
> 
>    # if the recipient is in the domain I secondary
>    if ($recip =~ /\@primary\.domain\.name\b/i) {
> 
>       # verify a known recipient on the primary
>       ($type, $msg) = md_check_against_smtp_server($sender,
>                         $recip,                # known recipient
>                         "secondary.host.name", # your backup/MX server
>                         "primary.host.name");  # the primary mail server
> 
>       if ($type  eq "REJECT") {
>          # the recipient doesn't exist, hard reject even if
>          # the primary is up
>          return ('REJECT', "Unknown Recipient");
>          }
>       elsif ($type eq "CONTINUE") {
>          # if you can verify it, then the primary is up
>          # TEMPFAIL (or REJECT) the message
>          return ('TEMPFAIL', "Only call me when the primary is down");
>          }
>       else {
>          # else, primary is down or having problems
>          return ('CONTINUE', "OK");
>          }
>       }
>    }
> 
I'll look at this this week!
Looks like it will do the equivalent of milter-ahead also.
Thanks!!

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