Getting in a flap over copyright envelopes

A most concerned reader of this august weblog (indeed, it will be august for just a few more days, still September kicks in) raises a most interesting issue:
"I was interested to note in the most recent IP Insight mailout from the IPO [for non-UK readers, that's what we used to call the Patent Office] the following advice on protection of copyright:

"Additionally, a creator could send himself or herself a copy by special delivery post (which gives a clear date stamp on the envelope), leaving the envelope unopened on its return (ensuring you also know what is inside each envelope in case you do this more than once)... It is important to note, that this does not prove that a work is original or created by you. But it may be useful to be able to show the court that the work was in your possession at a particular date".
I am surprised that the IPO are advising this course of action since I believed that it was generally accepted that this is a waste of a stamp and would get nowhere in a sensible court. All that it demonstrates is that an individual sent themselves an envelope at a particular date. That envelope could have been empty and unsealed and a document added later, or could have contained a document, the flap closed by a couple of paper clips and the document replaced by another and subsequently sealed at a later date.
I'd be interested to know if the Kats or anyone has any experience of the "sealed envelope" argument being used in court, successfully or unsuccessfully?"
The IPKat has no experience of copyright enveloppage in court. He does however have a cupboard-full of similar envelopes, personally handed to him over the years by friends who were worried that they couldn't register their copyright in the UK and wanted proof of authorship. He agrees with his correspondent that they are not per se cogent from an evidential point of view (though at a pinch he could give evidence that he was familiar with the concents of each envelope when he received it). However, self-addressed and securely deposited envelopes are a wonderful cure for the sort of insomnia that is generated by the fear that no-one will ever know when the author had indeed created a work.

Merpel says, this could be a great business for the postal service to develop: a special surcharge for legible date-stamping. She adds, this sort of thing may be more use to a defendant, in showing that an alleged infringing work existed earlier in time than the claimant's work, than to the claimant in infringement proceedings.

As usual, readers' thoughts are welcomed.

Pushing the envelope here
The UK Copyright Service, which pours scorn on "poor man's copyright", here (Does anyone know who these people are? This website gives the impression of being somehow official ... )