Thanks to Dave and Paul for the answers. The problem I was having was
caused by my not having made the file a "shared file" before emailing it in
Outlook.

"Dave Peterson" wrote:

When I need multiple people to update the same workbook, it becomes a serial
process. The workbook gets passed to person A and they have control--any
changes made to any other copies don't count for anything. It's just practice
(pronounced waste of time) for those people who do that.

Then when person A finishes the workbook, the either pass it to person B--or
they give it back to me. I make a backup copy of it and pass it on to person B.

That way when person B screws it up really bad, person A won't get mad--I can
just pass a copy of the backup to person B again.

=======
On the other hand, if your colleague is updating data in a completely separate
and distinct worksheet in that workbook, you could send them the single sheet.
Then when you receive it back, you can copy that data on the sheet in your
"master" workbook.

But if the data is in the same worksheet, don't try to update separate copies
and combined them later. The merging becomes more work than it's worth.
There's just too much that can change.

Melanie wrote:

I have an excel workbook that a colleague and I both need to update and email
back and forth. How can we do this?

--

Dave Peterson