process of resending message in webmethods EDI

Good afternoon

We are using webmethods EDI system to send & receive message with partners.
And I have a concern about the auto-resend by the system.

Can anybody help ?

Now, If I have a new message to be sent to the partner, and the status of EDIINT is as follows.
[processing stauts]. done.
[User Status]. SendMsg.WAITMDN.
it means we are waiting for EDIINT MDN from partner.

In this case, my question is, by system job, Can we retry to send to that partner 500 seconds later?

currently, our Setting value is as follows. in [Partner profile / Delivery Settings]
Delivery Maximum Retries = 3
Wait Between Retries ; 500000 (milliseconds)
Retry Factor. 1

but we have an error message like bellows. Connection reset
com.wm.lang.flow.FlowException:sender and/or receiver unknown