Overview
Visual preview is one of three deployment modes available for the Opensense Outlook Add-in. When enabled, the add-in renders a live HTML signature directly inside the Outlook compose window, giving users a visual representation of their signature while composing. This article covers how visual preview works, what it supports, and where its boundaries are so admins can make an informed decision about whether it fits their organization's requirements.
If you haven't reviewed the deployment modes side by side, start with the Outlook Add-in Overview before reading this article.
How visual preview works
When a user opens a new compose window in Outlook, the add-in renders their assigned HTML signature and inserts it directly into the compose window. The signature is applied client-side and exists in the email body before the user sends.
Because the signature is rendered and inserted in the compose window, it is visible and accessible to the user throughout composition. When the email is sent, it goes to the recipient with the signature as-is. It does not route through Opensense servers for transformation.
What visual preview supports
Compose-window visibility
Users see their full rendered HTML signature, including any banners, while composing. This is the primary reason organizations choose visual preview: employees have clear confirmation that their signature is active on every email.
Automatic signature insertion
The add-in inserts the signature automatically on every new compose, reply, and forward when Automatic Signatures is enabled in Domain Settings. No user action is required.
Sender-based banner targeting
Banner campaigns can be targeted based on the sender's attributes, including department, role, and group membership. Rules that target based on who is sending the email function as expected in visual preview.
Basic analytics
Views and clicks can be captured for banners when the HTML is coded to support it. This provides basic engagement data for banner campaigns.
Inline images
Inline images are supported in visual preview across all Microsoft 365 Outlook versions. Enable Inline Images in Domain Settings and append ?inline=1 to all image URLs in the signature HTML.
Reply and forward signatures
Visual preview supports either a consistent template applied to all replies and forwards, or a designated reply template applied specifically to reply and forward actions. Configure this through signature assignment and routing.
Tradeoffs to understand before choosing visual preview
Compliance: users can edit the signature before send
Because the signature is inserted into the compose window before the email is sent, users can manually modify it, including text, formatting, layout, and content, prior to sending. Those edits are not tracked, blocked, or flagged by Opensense. The email reaches the recipient with whatever the user last left in the compose window.
This is a meaningful consideration for organizations that use email signatures to enforce brand standards, deliver legal disclaimers, or maintain regulatory compliance. If signature integrity on every outbound email is a requirement, visual preview does not provide that guarantee. The plaintext block and stamping modes apply the signature server-side and cannot be edited by users.
Compliance-sensitive organizations: If your signatures carry legal disclaimers, regulatory copy, or brand-governed content, evaluate whether user-editability is an acceptable risk before enabling visual preview.
Marketing: recipient-based targeting is not supported
Recipient-based banner targeting is not available in visual preview. Opensense cannot determine recipient attributes at compose time because the email has not been sent yet. Targeting logic that relies on who is receiving the email cannot run until the message reaches Opensense's servers, which visual preview bypasses.
If your banner campaigns rely on targeting based on recipient industry, account, or contact attributes, visual preview will not support those campaigns. Stamping and the plaintext block both support full recipient-based targeting.
Marketing: advanced analytics are not available
Because emails sent in visual preview mode do not route through Opensense servers, advanced analytics including detailed banner engagement data beyond basic views and clicks are not available.
Organizations running data-intensive banner campaigns or reporting on campaign performance should factor this into the decision.
First reply signature
A full signature on the first reply is only available when using a routed solution (stamping or plaintext block). Visual preview supports reply signatures, but the behavior on first reply differs from what routed modes can deliver.
Third-party platform compatibility
The Outlook Add-in in any mode, including visual preview, only applies signatures to emails composed in Microsoft Outlook. Emails sent through Outreach, Salesloft, Salesforce, or other third-party platforms are not covered. Use routed mail flow integrations for those platforms.
Outlook Mobile: account switching
On Outlook Mobile, the add-in only passes the primary account context to the API. If a user switches the From address to an alias or shared inbox, the add-in does not update the signature to reflect the switched identity.
This applies to all add-in modes, not just visual preview. It is a Microsoft platform limitation.
Rendering across Outlook versions
Different versions of Outlook may render the composed signature differently. Certain elements may be blocked or display differently in the compose window depending on the client version. Test rendering across your organization's Outlook versions before rolling out visual preview at scale.
When visual preview makes sense
Visual preview is a reasonable choice when:
Compose-window visibility is a meaningful priority for your employees or organization
Your banner campaigns use sender-based targeting rather than recipient-based targeting
Advanced analytics are not a core requirement for your marketing team
The risk of user-edited signatures is acceptable given your compliance requirements
Your organization sends encrypted emails via Microsoft sensitivity labels or other M365 encryption policies. Encrypted emails cannot be processed server-side by Opensense, and visual preview is the only add-in mode that delivers signatures on encrypted emails reliably.
If your organization requires signature compliance guarantees and the full Opensense marketing feature set, the plaintext block provides add-in pane signature visibility with server-side control, without the compliance and marketing tradeoffs of visual preview. See the Outlook Add-in Overview for a full comparison of all three modes.