Bypass RFC1035

K

kris1351

Verified User
Joined
Mar 17, 2006
Messages
21
We have 2 offsite companies we deal with that have gone through a tough switch over on their servers it looks like. The only problem is we have to send to them and their admins have all of their MX records pointed to IPs instead of names. Is there a way to configure Exim on DA servers to allow sending to these servers anyways?

all relevant MX records point to non-existent hosts or (invalidly) to IP addresses
 
He means can he somehow break the following rules:

1. MX records comprise two parts - the host and the record itself.

- Create the host with an IP address.
- Point the MX record at this host.

2. An MX Record cannot be an IP address

the answer would appear to be no.
 
Has to be a way because Yahoo and Gmail both can deliver to them in their temporary state so that means Qmail has the option. Exim has to have a bypass somewhere.
 
If what you need to do is point MX directly to an IP#, no you can't do that. Well you can, though you'd have to do it manually, because DirectAdmin won't let you.

and for good reason, because if you do, many mailservers will refuse to deliver to you.

But there's an easy work around.

Pick any domain you control.

Create A records for subdomains thusly (replacing example.com with the name of your domain which you're using for this workaround).
clientdomain.ext.example.com.
Click to expand...
pointing that subdomain to the IP# you want to use for the MX.

Then create the MX record.

There's NO requirement that the MX point to the same domain.

Jeff
 
That's not the question, my mail servers are fine. We are sending mail to a customer of ours on another complete network, we have no control over their equipment but they have theirs setup with IP instead of name on the MX. The Exim default config rejects whenever we attempt to send to them with the error above.

I would just like our config to allow us to send to those that do not setup their DNS MX properly instead of reject.
 
So just create a subdomain that points to their ip then use that for the mx.
 
Kris, I don't understand. If you're handling the DNS, then you're setting up the MX records and you can do as scsi and I have both written. If they're setting up the MX records on some other DNS server, then it's their problem.

DirectAdmin isn't going to allow you to set up DNS records against the RFCs; doing that breaks delivery and DNS.

So unless you've got enough pull to rewrite the DNS RFCs, you've got the two choices I've mentioned.

Plus one other: you can intentionally break DNS MX records from the command line, and then chattr the zone file for the domain's DNS to RO so DirectAdmin can't change it.

Of course once youv'e done that YOU are responsible for breaking DNS, and possibly email delivery, for that client.

Jeff
 
You are not reading it.

We are sending to someone else that we have ZERO control or care over how they run their systems.

They have a broken MX setup according to the RFC where they are pointing the MX to an IP instead of a name like it should be.

WE are attempting to send mail to them, but our Exim simply rejects sending to them because it sees the MX as an IP instead of a name so we cannot send to them. All their problems aside this is someone we have to deal with for our VoIP products that has a major issue with the RFC of course, but we cannot stop sending to them until they figure out their issue. We need to make it so our Exim can send to them regardless if they are pointed to an IP or Name on the MX.

We aren't trying to fix their problem, we are trying to find a work around on our side so we can send mail to them.
 
Email them and tell them the problem they will probably fix it.
 
scsi said:
Email them and tell them the problem they will probably fix it.
Click to expand...

They know the problem, they do not control their stuff so it will be who knows how long till they fix it. So till then I guess we just can't contact them or keep doing business with them.
 
You may want to read this Q/A in the official exim FAQ.
You just need to use the "allow_mx_to_ip" directive.

Next time you have a problem with a specific software, I suggest you read the official documentation and FAQ before asking at the control panel's forum, which has nothing to do with it :D
 
Well doing the seach in 20 different ways never yielded that result and considering everyone here is using Exim specific to a DA server it is the best place to ask. Thank you for finding that though.
 
Last edited:
You are right, sometimes it's better to ask here. I searched in Google for it too, without any results, then I looked directly at the FAQ and got lucky ;)
 
Insert this line:
Code: 
allow_mx_to_ip
or if this doesn't work:
Code: 
allow_mx_to_ip = true
somewhere near the top of your exim.conf file.

Don't forget to restart exim.

Jeff
 
You must log in or register to reply here.
Back
Top