If you are using the Select Recipients dialog (you get that when you open a
blank e-mail and click on To) you have to look carefully to make sure you
are selecting an e-mail address (it probably says SMTP or E-mail or Business
Fax etc. or some other indication--you may have to scroll over tithe right
to see this). Outlook returns both e-mail addresses and fax numbers in this
window for each contact who has both. Kind of goofy, but as far as I know
this strange problem has never been fixed. (Maybe somebody in Redmond
doesn't think it is a problem!).
There are some work-arounds. The simplest is what I outlined above.
Another is to send e-mail from the Contact's window (click on Actions, New
Message to Contact), but this doesn't help much with cc's. Yet another
method I have read about is to wade through all your contacts and insert
something like "Fax" in front of the Contact's fax number; this is supposed
to prevent OL from thinking the fax number is a valid e-mail address (Why it
thinks a fax number is an e-mail address is a mystery). You can buy
software that does this for you (e.g.,
http://www.yousoftware.com/perform/sperry.php?keyword=sperrysite).