A friend of mine writes children's books, mostly non-fiction about exciting subjects like earthquakes and tsunamis and aliens.

Once she has finished researching and writing a book she sends it off to an editor, who checks it and then passes it to a designer who lays out the pages properly. She then has to check it all before it gets printed.

When she started as a writer that meant getting printouts of the books, and in order to make sure that they arrived on time most of the packages were sent by courier or recorded delivery.

Now, of course, a lot of it is done electronically, and e-mails whizz up and down the internet. And instead of printed pages she can correct things on screen.

In theory it's a lot faster, but recently she's noticed a problem. The editors and designers she works with assume that every e-mail gets through. And they seem to believe that it doesn't matter how big the e-mails are.

So a couple of weeks ago she got a frantic message from a colleague asking if she'd done the corrections to a book when she hadn't even received the laid out pages.

It turns out that her editor had attached an eight megabyte file to the e-mail, and it hadn't been delivered. Probably this is because my friend's e-mail provider blocked it because it would have filled her inbox. But it might have been the editor's mail server, refusing to send anything as big.

The editor hadn't noticed an error message, but there are so many fake error messages that come from spam e-mails that many of us ignore every one, even the ones that are useful. And often mail servers will simply give up without even trying to report the error.

We're all encouraged to believe that in these days of superfast broadband it doesn't matter how big files are. And everyone who takes digital photos likes to send the highest resolution pictures to their friends and family. But some parts of the internet haven't caught up yet, and e-mail is one of them.

It's still unwise to send anything more than a megabyte as e-mail. If you really have to send big files then there are websites that let you upload the file you want and e-mail your friends with details of where to find it.

Although I still find it's faster to burn a CD with all the photos I want my sister to see and just pop it in the post!

Another problem with sending e-mails is that there is still no reliable way to know that they have arrived safely or been read.

If you're making a phone call and the line goes dead at least you can tell. And when someone drops out of an instant message conversation the system will tell you that your message can't be delivered. But when you send an important message you're in the dark unless the person at the other end bothers to tell you they've got it.

Some mail programs, like Microsoft's Outlook, let you ask for notification that a message has been read. But if you e-mail someone who doesn't use Outlook this won't help you much.

The problem is that when e-mail was invented back in the 1970's nobody thought it would ever become so important or widespread. And so there was no standard way of checking whether messages arrive.

As far as the internet is concerned every e-mail is like a message in a bottle. You throw it out to sea and hope the currents will get it to the right place. And now there are so many different e-mail programs being used it's hard to see how it can be sorted out.

Of course the downside of reliable e-mail delivery is that you can't claim that a message didn't arrive to excuse your own laziness. And if your boss or boyfriend knew that you hadn't read their message for a week they might not be pleased.

Perhaps that's why we put up with the current situation and aren't crying out for e-mail recorded delivery! But it does mean that I'll often end up making a phone call, just to check that an important e-mail has arrived.