Before attaching an image to an e-mail, ask yourself some questions.

What do you want the recipient to see?
If all you want to do is show them a small illustration then don’t send the original, probably king-size image. It’ll probably have to be scrolled on their screen so they’ll only see a bit at a time of an image of a size larger than their e-mail window. Pixel dimensions of something like 600 by 400 are about the maximum usually appropriate and you can often get away with much less.

What might they to do with it?
If they need it for artwork for printing then they will need a maximum resolution copy – at the dimensions required. So find out what size in inches or centimetres they need and use a resolution of at least 200 pixels per inch. It’ll be a sizeable file so the next section is important. You may have to think about other methods of getting it to them.

If they need it for showing on screen then a resolution of about 72 pixels per inch is fine as few monitors display more than 100. For web use, you could compress the image to further reduce the file size and, as there is only a limited range of colours that can be displayed by browsers, it may be worth previewing what you’re sending at various compression and colour depth levels and you’ll see what you can get away with.

What connection speed do they have?
If the recipient is still on a dial-up internet connection then they will not appreciate having to wait for ages while your image downloads unless they have specifically asked for certain sizes. As a general rule, a 100Kb file will take about 15 seconds. No-one on dial-up will be happy waiting for anything measured in Mb so beware.

Broadband users should be able to manage most things you can throw at them, however.

What connection speed do you have?
The same applies at your end too, although it may not seem as important. Just remember that pressing Send will merely start the process and it may be several minutes before your message has actually set off on its journey.