I found a document in the R6 Admin Help that says:
When the Router is unable to transfer a message on the first attempt, it continues to attempt delivery at intervals, as specified in the “Initial transfer retry interval” field of the Configuration Settings document. If a message cannot be delivered (or forwarded to the next server on the path to the user’s mail server) within a specified time-out period, the Router returns a delivery failure report to the sender. By default, the message time-out value is 24 hours.
In the event that mail files on certain servers become unreachable for an extended period, consider increasing the default time-out value on other servers. A higher time-out value decreases the likelihood of important mail being returned because of transfer and delivery failures.
On the Internet, the time-out value for message transfer is typically five days - that is, if the next hop server is unreachable, the connecting server continues to retry transfer for five days before giving up and generating a delivery failure report.
OK, where do I reset the 5 day setting? I can find the MailTimeout setting in the INI file but nowhere do I see anything that will reset the 5 day setting. My client wants me to set it at 1-2 days at the most.