Mailbox apps

Send documents from the Gmail add-on and Outlook task pane

The Gmail add-on and the Outlook task pane both live inside the message you are already reading. Open the add-in on an email, confirm what each attachment is, and send it straight into Document Review — no download, no re-attach, no forward.

10 minute setup · Updated July 27, 2026

Both add-ins are message-scoped only.

Each one reads the single message you have open, and only while you have it open. Neither watches your mailbox, reads message bodies, changes labels or folders, marks anything read, or sends mail on your behalf. If you need to work several emails at once, that is the Chrome extension's job, not the add-ins'.

Which client to use

Conterminal has three ways to get an attachment out of a mailbox, and they overlap on purpose. The add-ins and the extension all end at the same place — a queued item in Document Review — so pick on where you are working, not on what you are sending.

Gmail Workspace add-on: The right choice when you are inside one message, and the only Conterminal client that works in the Gmail mobile apps. One message at a time.
Outlook task pane: The right choice in Outlook on the web, new or classic Outlook for Windows, and Outlook for Mac — including the desktop clients, where a browser extension cannot reach. One message at a time.
Conterminal Mail extension: The right choice when you are triaging a list in Chrome and want to send from several emails in one pass. Gmail and Outlook on the web only. See the extension article.
Email forwarding: Still supported and still the fallback for anything the add-ins reject, including a Word delivery order. See forwarding delivery orders by email.

Two practical differences decide most cases. The add-ins are the only option on a phone or in a desktop Outlook client. The extension is the only option when you want to select more than one email before sending.

Gmail Workspace add-on: install, open, send

Getting it installed

There is no Google Workspace Marketplace listing to install from yourself. The add-on is deployed as a Google Workspace add-on deployment named conterminal-gmail-v1 and installed for named users by whoever owns that deployment. If Conterminal does not appear in your Gmail add-on rail, that is an administrator task — ask them, and do not spend time hunting for it in Marketplace.

The add-on requests exactly three Google scopes, and no more:

gmail.addons.execute: Lets the add-on run inside Gmail at all. Nothing works without it.
gmail.addons.current.message.readonly: A temporary, current-message-only read grant. It is what lets the card list the attachment names on the email you have open. It does not grant access to the rest of your mailbox.
userinfo.email: Confirms which mailbox address authorized the add-on. That address is what Conterminal matches to your user account.

The broad gmail.readonly scope is deliberately not requested here. If a consent screen ever asks you for full read access to Gmail in the name of the Conterminal add-on, stop and contact support.

Opening it on a message

Open the email. The card is driven by an unconditional contextual trigger, so Conterminal loads on whatever message you open — there is no keyword or sender filter. On mobile the launcher sits in Gmail's bottom add-on row; Gmail owns that placement and Conterminal cannot move it.
Read the card header. It is titled Send to Conterminal, with the message subject as its subtitle. If Gmail cannot supply a subject, the subtitle reads Open message.
Pick a workspace if you are asked. A Workspace dropdown appears only when you belong to more than one active workspace. With a single workspace it is chosen for you and never shown.
Confirm each attachment. With one eligible attachment you get a single dropdown labeled with the file name and no checkbox — that file is always included. With two or more, each file gets its own checkbox labeled with the file name and the option Send this attachment, pre-checked, plus a Document type dropdown.
Set the document type. The choices are Delivery Order, Proof of Delivery, and Other Document. Conterminal pre-selects a guess from the file name and the subject line. It is a guess; you are responsible for the value you send.
Send. The button reads Send to Conterminal when there is one attachment and Send selected to Conterminal when there are several.

Gmail cannot close the card for you.

When every file is accepted, Conterminal shows a native Gmail notification and replaces the form with a compact Sent to Conterminal card that cannot be submitted again. That is the end of the flow — the add-on sheet stays on screen because Gmail exposes no way for an add-on to dismiss it. Close it with Gmail's own close control or gesture, or just move to the next message. Nothing is pending and nothing is waiting on you.

The confirmation text tells you exactly what happened: “Attachment sent to Conterminal.” for one file, “3 attachments sent to Conterminal.” for several, “Already sent to Conterminal.” when Conterminal already had that exact file, or a combined form such as “2 sent to Conterminal; 1 already sent.”

If anything was rejected, you get a different screen — a Conterminal submission card reading “2 queued, 0 duplicate, 1 rejected.” followed by “Move to the next Gmail message to continue.” and an Open Document Review button. Treat any non-zero rejected count as work still to do.

When a message has no eligible files, the card says “This message has no supported PDF, Word, or image attachments.” That wording is wrong about Word. The add-on only ever lists PDF, JPEG, PNG, and TIFF files, so a .doc or .docx delivery order will never appear no matter what the message says. Save it as PDF, or forward it to your intake address instead.

Outlook task pane: install, sign in, send

Getting it installed

The Outlook client is an Office add-in, not a browser extension. Its manifest is served from https://www.conterminal.com/mailbox-addins/outlook/manifest.xml, and the supported rollout is central deployment by your Microsoft 365 administrator. Three things have to be true on the Entra application before sign-in can work at all, and all three are administrator work:

Nested app authentication is configured for the task pane, with brk-multihub://www.conterminal.com registered as the broker redirect URI.
The Conterminal API scope is exposed on the application and matches what the task pane build was configured with.
Mailbox permission stays at ReadItem. The Office add-in does not use Microsoft Graph and must not be granted Mail.Read. If your security review sees a Graph mail permission requested for this add-in, it is looking at the separate Chrome extension registration, not this one.

The manifest requires Outlook mailbox requirement set 1.8. Anything older will not load the add-in.

Microsoft: centralized deployment of add-ins Microsoft: nested app authentication

Opening the pane

Open a message, then use the Conterminal group on the message ribbon and its Send documents button; its tooltip reads “Review and send this message's attachments to Conterminal.” The pane opens about 450 pixels tall and supports pinning, so you can leave it open while you move through messages. Its own header reads Send documents.

The pane loads in two stages, and the status line at the bottom is the thing to watch. It starts at Loading message..., then settles on Review attachments once your Conterminal session is established, or No supported attachments. if the message has nothing eligible. Sign-in is silent when it can be — Outlook only shows a Microsoft popup if a fresh consent is needed.

Sending

Choose a workspace if the selector appears. As in Gmail, the Workspace dropdown shows only when you belong to more than one. Leaving it on Choose workspace and pressing send gives you “Choose a workspace.”
Uncheck what you do not want. Every eligible file starts checked. Clearing them all and sending gives you “Select at least one attachment.”
Set each document type. Same three choices as Gmail: Delivery Order, Proof of Delivery, Other Document.
Press Send selected to Conterminal. The button changes to Sending... and the status line reads Sending attachments... while bytes are read out of the message and posted.
Read the result. The status line ends on a count in the form “2 queued, 0 duplicate, 1 rejected.” Use the Open Document Review link at the bottom of the pane to go work them.

Outlook mobile is not supported.

The Outlook add-in ships for Outlook on the web, new and classic Outlook for Windows, and Outlook for Mac. Outlook for iOS and Android are excluded because their API surface does not hand attachment content to an add-in under this permission model — this is a platform limit, not a setting you can turn on. On a phone, use the Gmail add-on if the mailbox is Gmail, or forward the message to your intake address.

The pane can also fail before you get anywhere near an attachment. “This Outlook client does not support secure add-in sign-in.” means your Outlook build does not offer nested app authentication and needs updating. “Microsoft mailbox add-in is not configured.” and “Microsoft mailbox add-in scope is not configured.” both mean the deployed build is missing its registration values — an administrator problem, never an account problem. Do not retry your sign-in for either of them.

Supported clients

Where you are	Client	Notes
Gmail on the web	Workspace add-on	Open message only. The Chrome extension is the better choice here if you want multi-message selection.
Gmail on iOS and Android	Workspace add-on	The only Conterminal mailbox client that runs on a phone. Launcher lives in Gmail's bottom add-on row.
Outlook on the web	Office task pane, or the Chrome extension	Both work. They are separate installs with separate Entra registrations; installing one does not install the other.
New and classic Outlook for Windows	Office task pane	Requires mailbox requirement set 1.8 and a build that supports nested app authentication.
Outlook for Mac	Office task pane	Same requirements as Windows.
Outlook for iOS and Android	Not supported	No add-in. Forward the message to your intake address instead.
Any other mail client	Not supported	Apple Mail, Thunderbird, and everything else have no Conterminal client. Use email forwarding.

Eligible attachments and limits

Both add-ins filter the attachment list before you see it, so a file that is missing from the list was excluded rather than hidden. Only six extensions are ever listed: .pdf, .jpg, .jpeg, .png, .tif, and .tiff. Inline images — signature logos, anything pasted into the body — are excluded, and in Outlook so is anything that is not a true file attachment, which means an attached message item or a OneDrive or SharePoint link attachment never appears.

Attachments per send: 20. Beyond that the whole submission is refused with “Select between one and 20 attachments.”
Total bytes per send: 100 MB. Crossing it stops the run at that point with “Mailbox submission exceeds the 100 MB byte limit.” — earlier files in the same send are already queued.
Delivery Order file types: PDF, DOC, or DOCX server-side, but the add-ins never list DOC or DOCX. Mismatch this and you get “Delivery Orders must be PDF, DOC, or DOCX files.”
Everything else: PDF, JPEG, PNG, or TIFF. The rejection reads “POD, Interchange Receipt, and Other documents must be PDF, JPEG, PNG, or TIFF files.”

Conterminal recognizes a fourth document type, Equipment Interchange Receipt, that neither add-in offers in its dropdown. Conterminal still guesses it from the file name and subject, and the two clients handle that mismatch differently and badly. In Gmail the guess simply matches no option, so nothing is pre-selected and you must set the type yourself. In Outlook the guess is held behind an empty- looking selector, and sending without touching it files the document as an Interchange Receipt anyway. If the document type box looks blank, set it explicitly before you send.

Sending the same attachment twice is safe. Conterminal keys each submission to the provider, the mailbox identity, the message, and the attachment, so a repeat comes back as a duplicate — “Already received by Conterminal.” — instead of creating a second review item. Accepted files report “Queued for Conterminal Document Review.” and land in the normal Document Review queue.

Your mailbox is never modified. The source message keeps its folder, its labels, and its read state, and the email body is never sent to or stored by Conterminal.

Linking your account

The provider proves which mailbox you are. It does not prove which Conterminal user you are. If your verified mailbox address matches exactly one Conterminal user who is active and belongs to at least one active workspace, the two are linked automatically and you never see this step. Otherwise you get a link prompt.

In Gmail that is a card titled Link Conterminal account reading “Enter the email address you use for Conterminal. We will send a single-use sign-in link.”, with a Conterminal email field and a Send link button. In Outlook the status line reads “This Microsoft account is not linked to an active Conterminal user.” and a Conterminal email field appears with a Send single-use link button; the main send button stays disabled until the link completes.

Enter the address you sign in to Conterminal with. Not necessarily the mailbox address. If they differ, this field is the one that has to be right.
Send the link and open the email. Both clients then say “Check your email for a single-use Conterminal link, then reopen this add-in.” — the Gmail wording ends in “add-on”. The link is valid for 15 minutes and can be used once.
Follow the link, then come back. It signs you in and drops you on Document Review. Close and reopen the add-in on the message; it will pick up the new link.

A “check your email” message does not prove an email was sent.

Both clients report the same success in three different situations: when the email really was sent; when the address you typed belongs to no Conterminal user at all, in which case the server deliberately stops without sending anything; and when a cooldown suppressed it — the same mailbox and address within the last five minutes, or five link requests from that mailbox within the last hour. If no email arrives, do not keep pressing send. Confirm the exact address you use to sign in to Conterminal, wait five minutes, and try once more.

Every send is re-authorized from scratch. Conterminal signs a capability scoped to that one message, those exact attachment IDs, and the document types you chose, and it expires after five minutes. Your workspace membership is rechecked at submission time, so a revoked user, a disabled mailbox integration, or a removed membership fails at send, not at install.

Troubleshooting

“This Outlook client does not support secure add-in sign-in.”

Your Outlook build does not offer nested app authentication, which the pane requires before it will request a token. Update Outlook, or use Outlook on the web. Nothing about your Conterminal account is wrong and retrying will not help.

“Only file attachments can be sent to Conterminal.”

Outlook handed back something other than raw file bytes for that attachment — typically an attached message item or a cloud link attachment rather than a real file. Save the document to disk, attach it as a file, or forward the message to your intake address.

“Outlook could not load the Office add-in runtime.”

The pane could not load Microsoft's own Office.js script, so nothing else in the pane will work. This is a network or content-blocking problem between your machine and Microsoft, not a Conterminal outage. Close the pane, check that appsforoffice.microsoft.com is reachable, and reopen it.

“Microsoft mailbox add-in is not configured.” or “Microsoft mailbox add-in scope is not configured.”

The deployed task pane is missing its Microsoft client ID or its API scope. This is a build and registration problem. Tell your administrator which of the two messages you saw; do not reinstall or re-sign-in.

“This Microsoft account is not linked to an active Conterminal user.”

Your mailbox is verified but not tied to a usable Conterminal user. Use the Conterminal email field and Send single-use link that appear with this message. If you are certain the address is right and the link never completes, your user or workspace membership is probably disabled — an administrator has to restore it.

“Open an Outlook message to use Conterminal.”

The pane is open without a message selected, or on something that is not a mail item — a calendar item, for example. Open a message in the reading pane or its own window and try again.

“Open this add-in from an Outlook message.”

Office reported a host other than Outlook. This normally means the task pane URL was opened directly in a browser instead of from the Outlook ribbon. Go back to Outlook and use the Send documents button.

“This message has no supported PDF, Word, or image attachments.”

The Gmail card found nothing it can send. Despite the wording, Word files are never eligible — only PDF, JPEG, PNG, and TIFF are. Inline images and signature logos are also excluded. Convert a Word delivery order to PDF, or forward the message to your intake address.

“Choose a document type for <file name>.”

A Gmail attachment was submitted without a usable document type. Reopen the card, set the type on that specific file, and send again.

“Delivery Orders must be PDF, DOC, or DOCX files.”

You classified an image as a Delivery Order. Change the type to Other Document, or send the PDF version of the document instead.

“Mailbox submission exceeds the 100 MB byte limit.”

The send stopped part way. Files processed before the limit are already queued, so check Document Review before resending — then send the remainder in a second, smaller pass.

“Conterminal could not queue the attachments.” or “Conterminal could not authorize this submission.”

The document-intake service refused the submission or the capability could not be issued. Confirm you picked a workspace, then try once more. If it repeats, capture the exact message and the file names and contact support rather than resending repeatedly.

The result line shows a non-zero rejected count

“2 queued, 0 duplicate, 1 rejected.” means part of the send failed. Duplicates are fine and need no action. Rejections do — the usual causes are a document type that does not match the file extension, or a file the provider would not hand over. Fix the type and resend just that file; the duplicate guard protects the ones that already went through.

The sign-in link never arrives

Check the inbox of the exact address you entered, including spam. Then assume the address is wrong or a cooldown suppressed the send — the same mailbox and address within five minutes, or five requests within an hour, are both silently dropped. Waiting five minutes and retrying once is the correct next step; pressing the button repeatedly burns the hourly allowance.

Following the link lands on an error page mentioning mailbox_link_request_invalid

The link was already used, has expired past its 15 minutes, or you signed in as a different user than the address the link was issued for. Go back to the add-in and request a fresh link with the correct address.