Issue Mailchannels bypassed by domains on same server

[JurgenN]

I'm not sure where to ask this: Plesk or Mailchannels, but I'll start here.

I have installed the Mailchannels extension on my Centos/Plesk VPS (after getting a relay account with them obviously), and everything seemed to go smoothly. However, I found out that only mail sent to external domains are routed through Mailchannels. Mail sent to another domain on the same server is not routed through Mailchannels, but sent "internally" straight to the receiving domain.

Is this normal behavior? I'm guessing it's not, but I'm not sure. I would like to let all messages go through Mailchannels, both to "external" and "internal" domains. How can I achieve that?

 

[JurgenN]

Hm... no replies yet... The funny thing is, the situation that I want is mentioned as an unwanted default situation in an older topic: Issue - Local forwarding email with Postfix & Mailchannels

Anyway, I have raised a ticket with Mailchannels, and although they were extermely helpful in trying to achieve the desired results, they were not able to do so in the end and suggested to ask Plesk for help. So I will raise a ticket with Plesk. In the mean time I will keep this topic open, and add the information that Mailchannels support gave me:

"Thank you for your patience while we did some research around the local delivery bypassing your relay issue. This appears to be a configuration or setting in postfix or plesk that is allowing/instructing local deliveries to skip the smarthost relay configurations that enable MailChannels routing from your network/server.

We have been looking over message boards, forums and plesk/postfix documentation and have not been successful in locating a step by step guide on what to correct in order to force all outbound through this relay, however we have found many articles about plesk prefering to use the local handler regardless of how postfix has been configured. We cannot find confirmation that this issue has been fixed and would need to recommend that you open a case with Plesk and ask for their official work around or resolution steps.

There are some suggestions about removing your local domains from the /etc/postfix/main.cf file under the mydestinations = directive. According to postfix documentation on mydestination, any domains or senders listed here would bypass the outbound connector and skip the MailChannels relay/inspection and return delivery. More about mydestination here to help you set this as needed: http://www.postfix.org/postconf.5.html (Search for mydestination, it is the 6th match on the page). Remember to restart postfix after making any changes to main.cf.

If Plesk is not honoring the postfix settings after updating mydestination, opening a case with Plesk will be the quickest approach as there is not a lot out there about how to force the local routing with Plesk that applies to this scenario.

We can leave this case open and give you some time to try some mydestination settings updates to keep postfix sending everything through the relay. If you need to contact Plesk support, let us know if we can help in anyway and we can add them to this ticket or they can add our address. With any luck the mydestination directive is just mapping your local domains and allowing a bypass of the relay block. Please let us know the outcome and status and we will proceed however we are needed."

FYI: I tried all kinds of settings with the mydestinations directive, but it didn't work out.