You can see the message “IDOC is ready for dispatch (ALE service)” in the transaction BD87 and your IDOC’s cannot be send to the receiver system, then you need to check the related program is working as a background job or not ?

If you see a situation on your SENDER system via transactionBD87 like below ;

Then you need to check the program “RSEOUT00″ , if this program stops working because of any reason, then your IDOC’s cannot be sending to the RECEIVER system.

Search and solve the status and execute the program in the SENDER system, then IDOC transfer will start again ;