When I send JPEG images to people, the images are supposed to appear
on the message page as they open the email. I get them from other
people like that. Some recipients can do this, and others cannot. I
have many friends in South Africa. Many South Africans cannot. They
either have to go to a separate attachment file and open it there, or
more often than not, they cannot open the attachment at all.

Is there another more reliable format for me to save images in than
jpeg? Might it be the settings on peoples individual computers? Most
people have dialup systems in South Africa. Is it something to do with
that perhaps? I have a Mac.
The problem seems to be both with recipients who use Macs or PCs. I
would value answers and solutions please.

Some of the recipients may have higher security settings than others.
I have configured my email program not to open attachments
automatically. I'm sure I'm not the only one doing this.

Let's do some forensic investigation first.

When you said that the jpeg image should appear in the message area,
I'd assume that you must be using either rich text or HTML format and
not plain text, am I correct ?

You could try to solve the problem by setting your edited message to
be sent, to HTML. I've ever solved similar problems by doing so.

Are your friends Nigerian ?

You should check if you're sending the mails in HTML format (Outlook,
etc) and the security level in them.  If you are ok, then the
recipients dont receive in the same format (plain text) and they need
the attachment for view the files.

I hope it helps.
Phossil