DNSs, MXs and RBLs....

["Santiago Barahona" <sant-bar () dsv su se>]

Hi all,

I have a question....

Once upon a time, there were two companies that created one new entity
(let's say 50-50)... one of them provides the IT infrastructure and the
other "the name" (i guess): it is company A's mail servers, and company
B's domain name...

Since the new users will be in company A's infrastructure, their mailboxes
will be hosted in company A's mail servers... but the domain name will be
controlled and hosted by company B... to do this someone has suggested to
company B to modify their DNS entries to point to company A's domain
name....

So when a MTA tries to reach user () newco com, it will find in Company B's
DNS that it points out to companyA.com, then it will go ask a DNS who is
companyA.com and deliver the mail... (tell me if I'm wrong)...

At first glance it looked OK but then it started to cause me trouble when
I thought about the case when the users of this domain start sending mails
because I think that company A's mail servers risk of being "black listed"
by some RBLs... if this happens not only the users of the new entity will
be percieved by spam but all users that use those servers...

Any light??... is it possible to get blacklisted this way??... do you have
any suggestions on how to avoid the risk??

or should make a risk analysis and present it to management in order to
get it to be accepted or not??

Many thanks for your remarks and suggestions!

cheers,

santiago