I think this is a bug that should be fixed.  i am using V 9.08

Issue: When using Member API and disabling account control, updating profile removes email address from member account.

In the file functions/functions_member_API.asp I have the following set:

Const blnMemberAPI = True
Const blnMemberAPIDisableAccountControl = True
Login, Logout, Register links are set to pages outside forums

I have looked in the code in /register.asp and found that on line 1632 this form tag is the problem, by using the DISABLED form tag.

<input type="text" name="email" id="email" size="30" maxlength="60" value="<% = strEmail %>" tabindex="5" <% If blnMemberAPI AND blnMemberAPIDisableAccountControl Then Response.Write(" disabled=""disabled""") %> />

Changing to using READONLY form tag like this fixes the problem:

<input type="text" name="email" id="email" size="30" maxlength="60" value="<% = strEmail %>" tabindex="5" <% If blnMemberAPI AND blnMemberAPIDisableAccountControl Then Response.Write(" readonly=""readonly""") %> />