microsoft exchange multiple send connectors

Question

I have and exchange server 2010.

Till now my ISP was providing me reverse dns service, so the mail server was working without problems.

Now we changed to new ISP for higher speed, we still have a static IP, but the new ISP doesn't let us to set a PTR record, so the mail server IP now is giving a null result when a PRT query is run over it.

This might cause problems in email delivery, but only when sending emails to very few hosts, the ones that check the PTR record.

To solve this, I tought to buy a smart host service to use as a backup solution to send emails.

My purpose would be to send only the problematic emails using this smart host, and not to use it for all emails, as the smart host cost depends upon the number of emails sent using it.

So I would like to create 2 send connectors

connector 1 - using DNS to route - cost 10 connector 2 - using the smart host - cost 20

And to configure a failover from from the first to the second connector in case the first connector fails to deliver the email.

Is it somehow possible to do this with exchange 2010 or 2013?

Is there any other way to solve my problem? I would not like to configure the second connector for each problematic domain, as this would require me to add time by time new domains to the connector....