Sheimaa Al-Awady Thanks for posting your question in Microsoft Q&A. Based on the description above, it seems that you are using Send Message Rest API to send message to Service Bus.
MessageId
they refer is part of BrokeredProperties and needs to be set on the client application side when sending the message (i.e. Azure Service Bus does not generate a unique message ID for each message sent.). Refer to https://learn.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads doc for more info (or ServiceBusMessage.MessageId Property) and make sure to set the property as described.
If in case you use any library in your client application, refer language specific doc for guidance.
I hope this helps and let me know if you have any questions.
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