SMTP Backup - Undone recent changes, but not fixed!

DNS MX config

Ok, so MX records just have priority assigned to them. By having multple entries with different priorities, does not accomplish your mail relay you would like setup.

If host A has SPAM filtering, and B is you exchange server.

Host A would exist in MX record only. Host A would have rules configured to take all mail belonging to Host B and forward them or relay them.

I hope I understood your problem properly.

Also, refer to http://en.wikipedia.org/wiki/MX_record for more info on MX record priorities

 

Hi Dave,
Im sorry, but I don't think that the standard Exim configuration with Cpanel is capable of doing what you want.

If I understand it correctly, you are talking about using Exim as an SMTP gateway like me$$agelabs, whereby your Cpanel server accepts all your incoming email, filters it, and sends it on.

However, the exim configuration within Cpanel does not support this - it is set up for mail performance, so it routes mail via the quickest route it can. As it is processing through the routers for your mail, it will see "lookup" as the transport, will perform an MX lookup on your domain, and find that itself is the primary MX. As this would cause a mail loop, you get your error.

The other problem is that a number of spam-senders send to the secondary MX to start with to try and avoid mail filtering.

What you would need to do is run a second instance of Exim with a seperate routing-config which uses a manual-routes table to lookup routing hosts:

1. Exim Daemon accepts the mail on port 25
2. Spamassassin processes
3. Spamassassin failed mail gets junked
4. Spamassassin passed mail gets queued in second Exim queue
5. Second Exim instance processes its queue, and uses the specific routes to deliver mail.

You could use MailScanner to achieve this (as it sets up two seperate Exim queues), or set it up from scratch yourself (the official Exim guide is a good start for this), but note that Cpanel will probably not support any email problems you have in this configuration.

I would have to add that it is probably too complicated to do this through forum-feedback, as you could run up against something which disables your mail while you wait for a reply - my advice would be to get an experienced admin (someone who has done it before) to do this.

To get you back up and running, either set Exim as the primary MX and use Dataenter.co.at 's PopBeamer to download and pass mail to Exchange, or set the MX's to be your Exchange server, however either way you are going to have to put up with the spam.

Rich