Every now and then we need to optimize our Outlook experience for our convenience. It comes out not just with outlook, but with all the websites that we use. We want to modulate the way we use the website according to ourselves. And here comes the need for plug-ins and add-ins. We have explored the possibilities and needs of common Outlook users and enlisted 25 MS Outlook plug-ins and add-ins.
A plug-in or add-in enhances the way we use the website.
So when you feel the need to install a plugin in your Outlook, this list is going to help you. You can choose from a wide variety of plug-ins and add-ins from the office store and other sources. The need of modulating the conventional way of using your mail has given rise to a number of people to develop supporting plugins for us. The internet is filled with so many useful plugins and add-ins for you.
AI Assistants for Outlook
1. Microsoft 365 Copilot in Outlook
Copilot is built into Outlook for organizations that license it, so there’s nothing to install. It started out drafting emails and summarizing threads. In April 2026 it became agentic: it now triages email, reschedules calendar conflicts, and surfaces priorities without being asked (Microsoft).
You can also ask it in plain language to organize messages, apply categories, create folders, and manage inbox rules.
Best for: companies already paying for Microsoft 365 Copilot.
2. Claude for Outlook
Anthropic’s official add-in runs in a sidebar inside Outlook. It summarizes long threads while citing the source email for each point, reads Word, Excel, PowerPoint, and PDF attachments without downloading them, and drafts replies in your writing style. It never
sends anything on its own; every draft waits for your review.
It’s currently in beta on Outlook for web, Mac, and Windows with Microsoft 365, and requires a paid Claude plan (Claude docs).
Best for: people who want an AI that connects email with their documents and spreadsheets.
3. MailMaestro
MailMaestro is a focused AI writing assistant for Outlook. It turns a few bullet points into a polished reply, summarizes threads, and flags emails that need a follow-up. It has a free tier for light use.
Best for: people without Copilot who mainly want faster replies.
4. Mailbutler
Mailbutler combines email tracking, mail merge, AI-assisted writing and follow-ups, shared inbox collaboration, and signature marketing in one add-in. It also works in Gmail and Apple Mail, which helps mixed teams.
Best for: small teams that want one subscription instead of five.
5. Grammarly
Grammarly checks grammar, clarity, and tone, and can rewrite emails with AI. Its older Office add-in is being retired; the company now recommends its Windows and Mac desktop apps, which work alongside Outlook.
Best for: anyone who writes a lot of professional email.
6. DeepL for Outlook
DeepL translates and rewrites emails directly in Outlook, and is widely regarded as more natural-sounding than basic machine translation.
Best for: international teams and multilingual communication.
Scheduling and Meetings
7. Boomerang for Outlook
Boomerang handles timing: scheduled sending, follow-up reminders, returning a message to your inbox if nobody replies, basic read receipts, and Inbox Pause. It’s one of the longest-running Outlook productivity tools and is still actively developed.
8. Calendly for Outlook
Calendly inserts your booking link or open time slots straight into an email, so you skip the back-and-forth of “what time works for you?” It suits sales calls, interviews, and client meetings.
9. Zoom for Outlook
Zoom for Outlook adds a Zoom meeting link to any calendar invite in one click. If your team uses Teams instead, that option is already built into Outlook.
Inbox Organization and Cleanup
10. SimplyFile
SimplyFile is a veteran from our original list that is still going strong. It uses AI to learn your filing habits and moves messages into the right folders with one click. It also supports thread cleanup and turning emails into tasks.
11. Advanced Folder Watch
Advanced Folder Watch alerts you when important messages arrive in specific folders, not just your inbox. It’s useful when rules route critical emails somewhere you might otherwise miss.
12. Clean Email
Clean Email is a bulk-cleanup service that connects to your Outlook account. It groups similar messages, unsubscribes in bulk, and applies automatic cleanup rules. It’s a good first step before adding any AI tool to a messy mailbox.
13. SaneBox
SaneBox works on the mail server rather than inside Outlook, so it works in every Outlook version. It learns which emails matter and moves the rest into a separate folder to review later.
14. Remo Outlook Duplicate Email Remover
Duplicate emails pile up after account migrations, failed syncs, PST imports, and misfiring rules, and they bloat your mailbox. Remo Outlook Duplicate Email Remover scans PST and OST files as well as Office 365 mailboxes, then finds and safely removes duplicates.
It’s a standalone Windows tool rather than an add-in, so it works regardless of which Outlook version you use.
Tasks and Collaboration
15. Todoist for Outlook
Todoist turns an email into a task with a due date and a link back to the original message. It’s good for people who use their inbox as a to-do list and want to stop.
16. Microsoft To Do (built in)
Flag an email in Outlook and it automatically appears in Microsoft To Do and Planner. It’s free and built in, and often all you need.
Security and Privacy
17. Report Phishing / Report Message (built in)
Microsoft’s built-in reporting button sends suspicious emails straight to your IT or security team, and to Microsoft, for analysis. Make sure it’s enabled; it’s one of the simplest security wins in Outlook.
18. Microsoft Purview Message Encryption
Included with many Microsoft 365 business plans, Purview lets you encrypt email and block forwarding directly from the Outlook toolbar.
19. Virtru for Outlook
Virtru adds end-to-end encryption, the ability to revoke access to a sent email, and expiration dates for sensitive messages. It’s popular in healthcare, legal, and finance.
CRM, Sales and Email Marketing
20. HubSpot Sales for Outlook
HubSpot Sales tracks opens, logs emails to your CRM, and shows contact details beside each message. It has a free version.
21. Microsoft 365 Copilot for Sales
Built for sales teams using Salesforce or Dynamics 365, the Outlook app surfaces customer context and recommendations, cuts manual data entry, and helps personalize outreach (Microsoft Learn).
22. PoliteMail
PoliteMail, an internal communications and email analytics platform, has been on this list since the beginning. It now offers its classic COM add-in, a modern Outlook add-in, and a standalone online version, all usable at the same time.
Documents, Signatures and Recovery
23. DocuSign for Outlook
DocuSign for Outlook sends attachments for e-signature and tracks their status without leaving Outlook. It saves real time on contracts and approvals.
24. Adobe Acrobat for Outlook
Adobe Acrobat converts emails and attachments to PDF and shares large files as links. It replaces the old “print tools” category for most people, since invoices are now usually archived as PDFs rather than printed.
25. Remo Repair Outlook (PST)
Some tools you only appreciate when something breaks. If a PST file becomes corrupted, or you’ve deleted emails, contacts, or calendar items you need back, Remo Repair Outlook PST rebuilds the file and recovers the data. It works with PST files from all Outlook versions.
This matters more now than it used to. As companies move to the new Outlook, old PST archives are often the only copy of years of email. For moving or backing up Outlook data between computers, Remo Outlook Backup & Migrate covers the other side of the job.
