Outlook add-in

What the add-in does

When composing an email, the ribbon offers two buttons:

• Send securely: select files or drag in entire folders. The add-in encrypts them within Outlook before they are uploaded. Either TEPHIA SECURE sends each recipient their own link when the email is sent, and the password is in the email; or the link is in the email, and the password goes to the same recipients in a second email.
• Request documents: creates an upload box and puts its link into the email. The recipient uploads their files encrypted, without an account.

On sending, the add-in checks whether link and password have been fully distributed. You will find status and proof of delivery in TEPHIA SECURE under Proofs of delivery, as usual. The files do not go through your email system: Microsoft only sees the emails with link and password, never the files.

Prerequisites

• A TEPHIA SECURE account in your organisation for everyone who uses the add-in.
• Classic Outlook for Windows (Microsoft 365, Outlook 2021 and later), new Outlook for Windows, Outlook on the web and Outlook for Mac with mailboxes in Microsoft 365.
• Not supported: Outlook 2016 and 2019. Outlook on smartphones will follow later.

Setting up for the whole organisation (Microsoft 365)

For the administrators of your Microsoft 365 tenant (Global Administrator or Exchange Administrator):

1. Open the Microsoft 365 admin center: Settings → Integrated apps → Upload custom apps.
2. Choose the app type Office Add-in, then Provide link to manifest file and enter this address:
   https://tephia.com/outlook/manifest.xml
3. Decide who gets the add-in: all users, specific groups or individual people.
4. Deploy. It takes a few hours on Microsoft's side, one day at most, before the add-in appears in Outlook.

Updates to the add-in then arrive automatically; you do not need to redeploy anything.

Mailboxes on Exchange Server (on-premises)

1. Download the version for Exchange Server. Exchange Server rejects the standard version.
2. In the Exchange admin center, under Organization → Add-ins, click + and Add from file, then choose the file. Add from URL does not work with Exchange Server (error “constraintProvider”).
3. Make the add-in in the list available to the users in your organisation.

If your Exchange Server rejects this version too, use the version without the send check. Classic Outlook for Windows and Outlook on the web of your server are supported.

Installing individually

To try it out without involving your administrators:

1. Download manifest.
2. In Outlook: Get Add-ins → My add-ins → Add a custom add-in → Add from file and choose the file.

Whether individual users may add add-ins themselves is controlled by your Microsoft 365 administration.

Signing in

• With Microsoft: the add-in takes over the sign-in from Outlook. The first time, each person briefly confirms the permissions once.
• With password and second factor: the first time, a sign-in window opens. The sign-in then lasts 30 days for this Outlook. It can be ended at any time in the add-in or in TEPHIA SECURE via the account menu at the top right under Account, section Sign-in; it also ends when the password or second factor is changed.

The add-in can only send files and create upload boxes. You change password, second factor, users and plan in TEPHIA SECURE in the browser.

Password email

If the link is in the email, the add-in sends the password in a second email from the person's mailbox:

• Signed in with Microsoft (Microsoft 365): directly through Microsoft Graph, without a second window. The first time, the person confirms “Send mail as you” for this.
• Mailbox on Exchange Server: directly through the Exchange Web Services (EWS) of your server, also without a second window.
• Otherwise the add-in opens the password email through a mailto: link, and classic Outlook asks the first time whether the add-in may open “mailto”. Individual users then tick Remember my choice and choose Open. For the whole organisation, allow “mailto” by Group Policy, Intune or the registry (Office version 2408 or later):
  HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Office\16.0\WEF\ProtocolHandlers\9d95a3e1-3e70-5d80-8a50-a2919c47e429
  Value mailto (string) = Allow. Ready-made file: Download registry file.

Limits

• Per transfer as much as your plan allows: 500 MB (Starter), 1 GB (Team) or 2 GB (Business, Enterprise), 100 MB during the trial – as in the browser.
• Multiple files and folders are bundled into one ZIP file.
• The add-in appears only when composing an email, not when reading.

More help

The detailed guide for IT, covering hybrid operation, policies, network and troubleshooting, is available after signing in to TEPHIA SECURE under Administration → Guide. We are happy to answer questions about the setup: connect [at] tephia [dot] com.