is there a built-in function in Excel that tells whether a text string is a
valid email? (I don't mean whether the address exists or not, but rather if
it has exactly one "@" in it, then some letters, then a ".", some more
letters, etc)

I can build one, but before I do...

----------------
This post is a suggestion for Microsoft, and Microsoft responds to the
suggestions with the most votes. To vote for this suggestion, click the "I
Agree" button in the message pane. If you do not see the button, follow this
link to open the suggestion in the Microsoft Web-based Newsreader and then
click "I Agree" in the message pane.

http://www.microsoft.com/office/comm...lic.excel.misc