[boanerges]

I receive occasional messages which say, "(No Sender) and (No Subject); this message has no content."
Some dates are in 1969!
Additionally, I cannot delete them.

What is going on?

[Big Mac]

What happens when you try to delete these messages? What error message do you get?

Sometimes spammers send absolutely blank messages. It happens.

[besson3c]

What are you seeing in another client?

[Cold Warrior]

Like besson says, see what you get in another client or even webmail. If it's not there, force quit the iPhone mail app and relaunch. See what happens.