Windows Azure Queue can have a message content size up to 64KB per message. This updated was included in Version 2011-08-18 and newer. If you are still on old version, then Windows Azure Queue will have 8KB message.

 

This size 64KB refers to the size of the UTF-8 encoded message. The body of the request contains the message data in the following XML format.

A message must be in a format that can be included in an XML request with UTF-8 encoding. In the following example the highlighted message-content is considered as message content and its size can go up to 64 KB.

<QueueMessage>

    <MessageText>message-content</MessageText>

</QueueMessage>

 

So this 64kb actual message content, not the raw message length, or Unicode binary length, or base64 encoded length when sent via http content.

More Info: http://msdn.microsoft.com/en-us/library/dd179346.aspx