If you have turned off the reading pane (View-Reading Pane-Off) then the CloudExtend add-in will only be visible from the Messages tab on the ribbon bar when an individual email is open. If you're using desktop Outlook, Microsoft only displays the add-in while you are viewing an email. It ignores any user-based proxy settings or physical connections to shares or internet connections. Obviously Outlook checks at the recent files attachments with the NCSI function if a network communication exists.

Update, see this article to check if your Outlook supports add-ins for shared mailboxes In our case only files on network shares were greyed out. On a remote desktop server, this was a real issue as the local user isn’t an administrator. This setting requires local administrator access and an elevated Outlook to get rid of the checkbox. In a shared mailbox, in another user's mailbox, in an archive mailbox, or in a public folder. Notice the Always ask before opening this type of file is greyed out. eml file which is an attachment to another message.Ī. A digitally signed message is an example since digital signing relies on one of these mechanisms.Ī delivery report or notification that has the message class IPM.Report.*, including delivery and Non-Delivery Report (NDR) reports, and read, non-read, and delay notifications.Ī draft (does not have a sender assigned to it), or in the Outlook Drafts folder.Ī. Protected by Information Rights Management (IRM) or encrypted in other ways for protection. The reading pane is hidden (View->Reading Pane->Hidden) Outlook does not activate add-ins (they are grayed out in ribbon bar) if the current message item, in a compose or read form, is one of the following: Otherwise, if you’re on a company system, they may have the option disabled for a reason and you’ll have to ask your IT folks about it. Antivirus plugins commonly cause the issue. Outlook add-ins are available on messages or appointments while composing or reading, but not other item types. The problem were the option to read as plain text is grayed out is usually caused by some type of plugin that’s installed in Outlook.

Outlook attachments greyed out