[exim] what happens when a mail server changes it's IP numbe…

Hi,

We had a problem delivering to a domain yesterday as it looks like
their one and only mail server changed it's IP number (I've told them
to add another mail server to their MX record).
Exim continued to try to deliver to the old IP number until I deleted
the retry db files. If I hadn't have done that, would the message have
eventually timed out and bounce back to the sender?

Thanks,

Oliver