(English) Postfix: Backup MX

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  • Xcom

    Is it really necessary to add the permit_mx_backup ? In my first setup, I found that it worked as expected without permit_mx_backup.

    • http://makaronzserem.eu Maciej Lasyk

      No it’s not necessary, but due to some security reasons it’s good to use it (but remember to do it together with permit_mx_backup_networks). There were problems with backups MX over IPv6 DNS records – under some circumstances it was possible to inject some messages to the backup MX server from a spam-server in order to deliver it to the main mail server. I believe, that this is already patched, but I see no reasons not to use this particular configuration option.