You must be assigned permissions to send-as the group (alias) you select here. If you attempt to send-as a group, mailbox or other address without the necessary permissions, your message will not be delivered. Contact Support@webville.net or your local administrator to verify or request permissions.
Watch out for gotcha’s: If you simply type an address in the from field rather than selecting a directory object from the drop down search results, your message may not be delivered. If what you type is resolved to simply an email address rather than an actual object from the directory, sending will not be successful. It can be hard to tell the difference if the group alias you want to send from has a display name exactly like its address. Be particularly careful the first time you try to send from any particular group alias to click search and select the object from search results. To do this, type just a portion of the address and click search, even if the address you want is listed as a suggestion above the search button. It might be listed there only because you’ve typed it before and not because it’s a valid object from the directory.
After you have successfully sent a message from the group alias, it will appear in a drop down list when you click the From button. It’s only difficult and tricky the first time you try (like many things).