How to check for existing mail accounts?

Kevin Miller Kevin_Miller at
Tue Apr 1 16:07:11 IST 2008

Brian McKerr wrote:
> I have a Zimbra server which, of course, runs openldap and I *used*
> to do dynamic LDAP look ups to see if user accounts were valid from
> my MS/Postfix gateway. It worked well, but I have since changed to
> *not* use LDAP dynamically because whenever I do maintenance on the
> zimbra box, the gateway box cannot validate users and therefor
> bounces mail. Not good. I now have a script that runs every hour and
> it does an LDAP lookup and dumps all valid user account names into a
> file that then gets hashed for postfix to look up. Now I can leave
> the zimbra machine (vm) down for any amount of time during the night
> to take a 'cold' backup of it, without worrying about bouncing
> emails.          

One thing you can do is to have multiple MX hosts, so that when you do
service on one, it isn't listening to inbound traffic, hence no bounces.
All the traffic is handled by the other mail gateway(s).

The backups don't necessarily have to be that beefy - just powerful
enough to handle the load for a short time while you do the

Kevin Miller                Registered Linux User No: 307357
CBJ MIS Dept.               Network Systems Admin., Mail Admin.
155 South Seward Street     ph: (907) 586-0242
Juneau, Alaska 99801        fax: (907 586-4500

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