Hi Priyanka,
Please go to the below link and check if the particular adapter threads have been utilized completely.
Configuration and Monitoring Home -> Adapter Engine -> Adapter Engine Status -> Additional Data
In the above link if you find the threads for the particular adapter has been utilized completely, then restart the particular service. The stuck messages in delivering status will be successful. If you face the same problem again and again, then it is suggested to increased the number of threads allocated to the particular service.
Please let me know if you need more help on this.
Regards,
Nitin