Can I send batch messages larger than 256 KB to Azure Service Bus?

The short answer

NO!

The long answer

The Azure Service Bus maximum message size is 256 KB for Standard tier and 1 MB for Premium tier (https://docs.microsoft.com/azure/service-bus-messaging/service-bus-quotas).

A simple solution to overcome this limitation is split the messages in blocks lower or equal to 256 KB size.

Below is a simplified version of the code that I used for Standard tier case: