I am using the Send Notifications Tools to trigger adhoc emails to users but I am unable to edit the form email address section:
Learning Management System
System Admin -> Configuration -> Global Variables -> Mail Tab -> You will find a configuration as Send Notifications from:
which will be selected as Admin, so either add email address in your admin account (so that the system automatically populates the same email address in from email address section in Send Notifications tool)
or Change it to either Free form (Which will allow you to type the from email address while sending adhoc notifications)
or Select from the list (and provide the comma separated email addresses in the below box from which you can select one as from email address while sending from the tool).
Send Notifications Tool
Form email address Unable to edit from email address , KBA , LOD-SF-LMS , Learning Management System , LOD-SF-LMS-COR , LMS Core - Items, Catalog, Curricula , How To