Another option is to create a message rule. Do you know how to create
message rules? Please be careful if you do this, since a simple mistake can
cause you to lose important messages.
You can create a message rule to delete the message; I am not sure what
exactly would happen, but I assume the message would be downloaded but then
it would be automatically deleted. You can create a message rule to delete
the message from the server, so it won't even be downloaded. In either case,
the sender won't know you did not get the message.