Route outgoing internal mails via smarthost

[A Former User]

Dear community,

We’re using a setup with two mailgateways between our Kopano server and the internet… One gateway is set up in the dns as MX10 (this is the main gateway) and the other with MX20, used only as backup.

We also use the gateways for internal e-mails, so every e-mail in our company goes through the gateways. For this purpose the kopano-spooler is configured to use one of the mail-gateways as outgoing mail server, which then sends the internal messages back to the postfix service running on kopano. This works fine, but this way I cannot use both mail gateways.

With postfix you can use default_transport = smtp:domain.tdl:port to let postfix check via MX records - with kopano spooler this wasn’t possible.

Do you guys have a idea how to do this? DNS round robin is also not what i really want, because it doesn’t prioritize the gateways as it is possible with mx records. Setting the kopano-spooler back to the default setting, where it uses the local postfix as MTA would be a possibility, but as far as I know there’s no possibility to tell postfix to route internal mails also via smarthost without creating a loop.

Kind regards