Re: [LUG] Mail skipping MX

On 3 August 2010 11:30, Simon Williams <simon@xxxxxxxxxxxxxxxxxxx> wrote:

Morning all.

I'm having some trouble at a charity I've been helping out (bisc.org.uk). They're using 123-reg for DNS and mail forwarding. The MX records are set to 123-reg, then we have a bunch of A records for the website with Hostgator.

In the last couple of weeks, mail has been intermittently bouncing. What I don't understand is that the bounce messages are from Hostgator. It seems that there is some problem with the MX and so the mail servers are falling back to delivering to the A record. Is it possible that some mail servers are skipping the MX completely?

I called 123reg when this first happened and they couldn't see anything wrong. It was working again at that point, so I put it down to someone making a mistake somewhere. Now the problem is back, but it's still random whether it will bounce or deliver.

To be honest, all things point to a problem with 123reg, but does anyone have any other ideas, or know where I can get more information?

I agree that the mx records for bisc.org.uk look alright

Look at the route in the bounce messages and see exactly what is happening

The mail setup for 123-reg looks a bit crap. It looks like it could be possible under some circumstances that the mx secondary and primary are the same host. For example,
mx0 round robins to "94.136.40.151" which then fails. Then mx1 is looked up and the first entry is "94.136.40.151".

I would have thought this would lead to a straight forward bounce, not using the A records but....