[Exim] Detecting IP addresses in MX records

Hi all,

From the other thread about IPs in MX records, it looks like this
problem might be more common than I realized.

How can I detect an IP in a MX with a filter? I want to bug the mail
admin that does this each time my server delivers to their domain, but
still deliver to them.

It'll say something like what the error says to me "It looks like you
have an IP address in the MX record on $domain. Please read $url"

And $url will be a page on exim.org (hopefully) that will contain the
needed parts of the RFCs and a few paragraphs to explain what they
mean.

Maybe this can be put in the default config file (commented out, of
course but there still for the exim admin that wants to do so.)?

So, what do you think? Good idea or bad? The problem is I didn't
notice anything that would let me detect such a condition. Although,
I didn't do an exhaustive search.

Mike