Track changes for draft emails

Sideline is an Outlook Add-in that lets you use track changes on draft emails.

• Marking up the body of a colleague's draft email? Instantly see what you've changed, or automatically convert your edits from clean into track changes.
• Received your email back with the edits made in clean? Run a redline comparison with a single click.
• Received your email back with the edits shown in track changes? Use Sideline to accept or reject any of the changes.

Sideline is for teams that work collaboratively on crafting important email communications. Lawyers make up the large majority of users (across all practice areas, jurisdictions, and seniority levels), but we have users from other industries too.

By enabling a track changes / redline functionality within Outlook, Sideline supports on-the-job feedback & learning, and reduces time otherwise spent on tedious formatting tasks. It's useful whether you're a supervisor settling draft emails every day, or a junior team member eager to improve and learn from your more experienced colleagues. Sideline can even be used to enhance collaboration with external parties like clients, without them needing to install Sideline on their end.

Sideline is the original, pioneering Outlook track changes tool. It aims to do one thing, and to do it really well.

• Sideline offers a best-in-class design and user experience, minimizing clicks and avoiding the creation of new windows or new emails. For example, all actions involving the modification of text (e.g. converting to track changes, accepting/rejecting changes) happen in the existing, live Outlook email on screen - users don't need to go into another window to achieve this.
• Sideline is fast, accurate and reliable. It's specifically optimized for Outlook email redlines, rather than general text or document comparisons.
• Sideline is constantly innovating and 100% focused on one thing only - helping users with their email drafting workflows.

Sideline fits within typical back-and-forth email drafting and review workflows, rather than trying to change how people work. Most people happily use Sideline without any training or by clicking through our short product tour. That said, many people appreciate the opportunity of a 15-minute live onboarding session, which we offer at no extra charge.

Importantly, while Sideline is all about improving collaboration, there's no need for supervisors to touch Sideline if they don't want to. Supervisors can simply markup draft emails in clean, and once received by the original drafter, the original drafter can click one button in Sideline to see a redline. This makes change management and adoption much easier.

We offer a 14 day free trial. Cancel anytime, no minimum user numbers. No hidden costs. No tricks.

Contact us for a quote in a different currency, for information on volume discounts, or for information and pricing on self-managed deployments within your own Azure tenant. We serve customers all around the world.

Sideline is hosted on Microsoft Azure with full end-to-end encryption. No data (including emails) processed through our servers is ever stored on our systems. Customers can select from various server locations to satisfy their data residency needs.

Sideline has been independently security tested and we expect to obtain ISO27001 certification in January 2026. For enterprise customers, there is also the option to deploy Sideline within their own Azure tenant. Please get in touch for more information.

Sideline requires MS Outlook running MS365 or Office LTSC2021 (or later), with Exchange Online. All MS Outlook platforms are supported - Classic Outlook for Windows, New Outlook for Windows, Outlook for Mac, and Office on the web. Exchange Server is not supported.

Because Sideline has been built on Microsoft's modern, web-based 'Office Add-ins' platform, it won't interfere with Outlook or any other add-ins you have, unlike older style VSTO/COM add-ins. Deployment is performed centrally and takes around 5-10 minutes.

Please complete the sign up form to receive step-by-step installation instructions. You can also simulate the track changes / redlining experience in the clickable demo at the top of this page.