To expand upon @johnpowell‘s quip:
If you’re using Outlook and want to embed an image inline in your email (that is, where the photo shows up in the body of the message, not just as an attachment), I highly recommend ensuring your email is in HTML format (not RTF and of course not plain text).
You see, I’ve found that if an Outlook-created email is in RTF format, and you attempt to embed a .GIF or .JPG image in the message body, that Outlook will convert the image to .BMP. So your little 300KB jpeg file will get ballooned out to 4MB or other ridiculous size because bitmap images do not employ compression (and are flat out stupid for most purposes).
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In Outlook 2007, start a new email and:
– type your message
– place the cursor where you want the image to go
– click the Options tab – (you’d think Format Text, but no, this is MS)
– ensure HTML is selected in the Format portion of the ribbon
– click the Insert tab
– click the Picture button
– select the image you want to embed inline – (best if it’s GIF, JPG, or PNG)
– click Send
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Then, how your email is presented to the reader is also a function of what email client they employ. As others mention, Google will show no images by default, and the reader must enable images. Outlook does that for url-based (not directly attached images). Apple Mail does similar. So does Thunderbird. And then you’ve got UNIX mail geeks who only ever read plaintext from commandline and will hate you and your HTML-formatted message. You just can’t win them all.