Outlook client support and the add-in

Footer365 can work in two layers:

• At compose time, with the add-in. The Footer365 Signatures add-in puts the signature into the message while it is being written, so people can see it, and so it is in their Sent Items.
• Server side, for every client, with mail flow. The relay adds the signature as mail leaves Microsoft 365. This covers every Outlook client, every phone, every third-party mail app and every system that sends through your mailboxes, so nobody needs the add-in for their mail to be signed.

Most organisations use both. An organisation that chooses the Outlook add-in only has the first layer alone: only mail written in Outlook with the add-in is signed, and everything else is sent without a signature. Using the Outlook add-in only

When the add-in has signed a message, it marks it so the relay does not sign it again. See How mail flows through Footer365.

Which clients run the add-in

Apple Mail and Outlook 2016 or 2019

Apple Mail cannot run Outlook add-ins. The add-in's manifest asks for the Mailbox 1.10 requirement set below, on Windows and on a Mac alike, and Outlook offers an add-in only where its version supports what the manifest asks for. Outlook 2016 and Outlook 2019 bought outright, rather than the Outlook that comes with a Microsoft 365 subscription, are not among the versions Microsoft lists as supporting Mailbox 1.10, so the add-in is not offered in them either. Footer365 has no separate program to install for these clients.

• While writing. The Footer365 signature is not in the message, and it is not in the sender's Sent Items. A signature someone has set up in the program itself is still added as usual.
• With mail flow. Recipients get the signature. The relay adds it as the message leaves Microsoft 365, as it does for any other mail app sending through your mailboxes. Nobody needs to set anything up. The relay does not look for a signature someone set up in the program itself, and turning off people's own Outlook signatures does not reach these programs, because it changes only the signatures stored with the mailbox and Outlook on the web's setting. So a signature of their own set up in the program should be removed from it, or recipients get both. My signature appears twice
• With the Outlook add-in only. The message is sent without a Footer365 signature, because Footer365 never sees it. The Coverage page cannot count mail it never sees: someone who writes only in these programs is counted under Nothing signed, and shows as Not sending in the list, because the add-in signed nothing of theirs. To sign their mail, they add the signature to the program themselves, as below.

Seeing or copying your own signature. Everyone has their own page at https://app.footer365.net/Me. The My signature card shows their signature with their details as signatures use them now, and Copy for a computer copies it, with its layout, images and links, ready to paste into the program's own signature settings. How to add it opens the steps for Apple Mail and for Outlook 2016 or 2019. With mail flow, the card says the signature is added already, so a copy is only needed for a mail app that sends from somewhere else. Add your signature to other mail apps

Requirement set

The add-in's manifest requires the Mailbox 1.10 requirement set. That is the minimum for the two things it cannot work without: the compose event (OnNewMessageCompose) and the ability to set a signature in the message.

Events from later requirement sets are declared too. On a client that does not support them, they simply do not fire and the add-in falls back to what 1.10 provides.

The events it uses

Composing from a shared mailbox needs Mailbox 1.13 for the add-in to activate there. Below that, the server-side signature still applies with mail flow. With the Outlook add-in only, the message is not signed.

The ribbon button

When composing, the Footer365 group on the ribbon has a Footer365 Signatures button. It opens a pane listing every signature assigned to that person, each labelled with when it applies, and lets them insert a different one.

When your organisation has staff self-service on, the pane also has a My details tab, where the person sees the details their signature uses and changes the ones your Super Admin opened up. It uses the same single sign-on as the signatures, and only ever reads and changes the signed-in person's own record. Let staff edit their own details

When your organisation has written snippets that the person can use, the pane also has a Snippets tab, where they insert an approved text where the cursor is. It uses Outlook's setSelectedDataAsync, which needs only Mailbox 1.1 and the permission the add-in already holds, after asking getTypeAsync whether the message is HTML or plain text. A version of Outlook that does not let add-ins write to the message is offered Copy instead. Snippets your people insert from Outlook

Languages

The add-in is shown in English, French, German, Spanish or Dutch. It follows the language Outlook itself is shown in: the pane, the Snippets and My details tabs (though not the text of a snippet, which is your own wording), the notices Outlook shows while a message is written, and the add-in's name and ribbon button all appear in that language. A regional form, such as German for Austria, French for Canada or Spanish for Mexico, uses its language, and any other language uses English.

Each language was reviewed against Microsoft's own terminology and style guide for it, and the words Outlook itself uses, before it was switched on. Spanish addresses the reader informally, as Microsoft's Spanish style guides recommend.

The pane and its notices change as soon as Footer365 releases a language, with nothing to do on your side. The add-in's name and ribbon button come from the add-in's manifest, so they change when the latest version of the add-in reaches your organisation.

Only what staff see is translated. The administrator portal, the signature editor and the emails Footer365 sends stay in English. The signature itself is never translated: it is what your organisation wrote, in the language it wrote it. So are the names of your own fields and the choices you offered for them.

Settings Footer365 turns on for the add-in

Event-based add-ins only fire if your organisation allows them, and the add-in's single sign-on needs modern authentication. When mail flow is set up, Footer365 checks both and switches them on if they are off. See What Footer365 creates in Exchange Online. With the Outlook add-in only, Footer365 does not do this, so check both yourself: Using the Outlook add-in only gives the commands.

Limits worth knowing

• Large recipient lists. When Outlook stops reporting the full list of recipients, the add-in cannot prove every recipient is internal, so it uses the external signature.
• Deleting the signature. If someone deletes the add-in's signature before sending, the add-in lets the message through to the relay, which signs it on the way out. With the Outlook add-in only, the message goes without a signature, and the Coverage page counts it.
• Sent Items. Without the add-in, the signature is not in the sender's own Sent Items, because it is added after the message leaves the mailbox. See I cannot see my signature while writing.
• Deployment time. Microsoft can take several hours to push a newly deployed add-in to everyone. See Deploy the Outlook add-in and The add-in is not showing.