This is expected behavior. The email addresses stored in contacts are not simple text fields; each is a combination of three different text fields. You'll need to edit them on the General tab, not on All Fields.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> Should every field on the All Fields tab be editable? Some of the
> fields, for example "E-mail 2" will not permit inline field editing on
> that tab. Is this expected or configurable somewhere? Couldn't dig up
> any information on this in Microsoft's help, site, or newsgroups. I
> have users who prefer to use that tab to edit contact information and I
> can't see any reason why these should be greyed out.