Send a message to the given user.
<p>See {@link #convertAndSend(Object, Object, java.util.Map)} for important
notes regarding the input headers.
@param user the user that should receive the message
@param destination the destination to send the message to
@param payload the payload to send
@param headers the message headers
@param postProcessor a postProcessor to post-process or modify the created message
Send a message to the given user. <p>See {@link #convertAndSend(Object, Object, java.util.Map)} for important notes regarding the input headers. @param user the user that should receive the message @param destination the destination to send the message to @param payload the payload to send @param headers the message headers @param postProcessor a postProcessor to post-process or modify the created message