When sending a long SMS (multipart) with the registered delivery receipt flag, each and every segment would be registered with the DLR flag.
This makes the SMSC send a DLR for every segment of the message and you have to make a bigger effort on keeping their state, so you can merge the final state of the whole SMS.
I would like to request an `SmppConfiguration` option (i.e DlrOnLast) that would enable the DLR flag only on the last segment of the long SMS.
A possible work-around that should occur on the SubmitSm and SubmitMulti:
A possible better solution incorporating this would be to remove the DLR flag from the submit-sm template, at the first place.