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OutMass

Send personalized mail merge campaigns, track opens & clicks, and automate follow-ups — all from your Outlook inbox.·getoutmass.com

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$9–$19/mo · Free plan See pricing ↓

OutMass is a Chrome and Edge browser extension that adds mail merge and bulk email campaigns to Outlook on the web. It works with Microsoft 365 and Outlook.com accounts and sends every message through the user's own mailbox via the Microsoft Graph API rather than third-party servers. It offers open and click tracking, automated follow-ups for non-openers, and an AI email writer.

What it's for

Sending personalized mail merge email campaigns from OutlookTracking email opens and link clicksAutomating follow-up emails to recipients who haven't opened a messageRunning A/B subject line testsDrafting emails with an AI writerManaging unsubscribes and a suppression list

Features 18

13-language extension interface
A/B subject line testing
AI Email Writer (powered by Claude)
Automated follow-up to non-openers that stops once a reply is detected
Campaign reports
Click tracking
CSV export
Daily send limit spread over multiple days
Email template library
Mail merge with CSV contact import
Open tracking
Personalization merge tags ({{FirstName}}, {{Company}})
Priority support (Pro plan)
Reply detection that checks headers, not message content
Scheduled, server-side sending
Sends via Microsoft Graph API through the user's own mailbox
Unsubscribe and suppression list management
Works inside Outlook Web as a Chrome/Edge extension

At a glance

free tier

TypeBrowser extension

DeploymentCloud

PlatformsWeb

LanguagesEnglish, Turkish, German, French, Spanish, Russian, Arabic, Hindi, Simplified Chinese, Traditional Chinese, Japanese, Portuguese (Brazil), Portuguese (Portugal)

CompanyMetis Information Technologies Ltd

Integrations

Outlook.comOneDriveMicrosoft OutlookMicrosoft Graph APIMicrosoft 365Stripe

Pricing

Subscriptions are billed monthly via Stripe; a 30-day money-back guarantee is offered. No annual billing option is mentioned.

FreeFree

Mail merge, Open tracking, Unsubscribe & suppression list

250 emails / month

Starter$9/mo

Mail merge, Open + click tracking, Scheduled sending, Daily send limit (spread over days)

2,500 emails / month

Pro$19/mo

Everything in Starter, AI Email Writer (50/mo), A/B subject testing, Template library, Priority support

10,000 emails / month