How to Send a Mass Email in Outlook: 3 Ways Compared

TL;DR

• Outlook has three ways to send a mass email: a contact group, BCC, or a mail merge.
• Contact groups and BCC send one shared email; a mail merge sends an individual, personalized email to every recipient.
• For anything customer-facing, use a mail merge: it looks personal, keeps addresses private, and tends to fare better with spam filters than a BCC blast.

You have a list of people and one message to get out. What is the right way to do that in Outlook?

It depends on whether recipients may see each other, whether the message should feel personal, and how many you are sending. This guide walks through all three methods and when each one is the right choice.

The 3 ways to send a mass email in Outlook

Method	Recipients see each other?	Personalized?	Best for
Contact group	Yes, everyone	No	Small internal teams
BCC	No, but it reads as a broadcast	No	Quick one-off notices
Mail merge	No, each gets their own email	Yes, per recipient	Customers, clients, larger lists

Method 1: Contact group (distribution list)

A contact group is a saved list of addresses you can put in the To field.

1. In Outlook, go to your contacts (People) and create a New Contact Group.
2. Add members, save, and address a new email to the group name.

The catch: every recipient sees the full recipient list, everyone can reply-all, and nothing is personalized. Use it for internal teams, never for customer lists: exposing customer addresses this way can constitute a privacy breach.

Method 2: BCC

Put your own address in the To field and paste every recipient into BCC. Recipients cannot see each other.

The catch: the email typically arrives addressed to you or to “undisclosed recipients”, which reads as a broadcast to people and is a common bulk-mail pattern for spam filters. There is still no personalization, and one typo in the paste can leak your list into a visible field. If your goal is hiding recipients from each other, a mail merge does it without looking like spam; see how to send a mass email individually in Outlook.

Method 3: Mail merge (individual personalized emails)

A mail merge takes a spreadsheet of recipients and sends each person their own email, with placeholders like {{FirstName}} replaced by their data. No recipient ever sees another address, and every message reads like it was written for them.

With the SecureMailMerge add-in the whole flow happens inside Outlook:

1. Install the add-in from Microsoft AppSource (free for non-commercial use) and open a new email.
2. Upload your spreadsheet with a To column and any personalization columns, or pick recipients from your Outlook contacts.
3. Write your email and insert merge fields like {{FirstName}} in the subject or body.
4. Send a test email to yourself to check the result.
5. Start the campaign. Outlook sends one individual email per row, from your own mailbox, so replies come straight back to you.

It works in Classic Outlook, New Outlook, Outlook for Mac, and Outlook on the Web, and it can do things the other methods cannot, like individual attachments per recipient and CC/BCC per row. For the full picture, see the complete guide to mail merge in Outlook.

Before you hit send: limits and deliverability

• Know your sending limits. Microsoft 365 business accounts can typically send to 10,000 recipients per day; personal accounts far fewer. Details: Outlook email sending limits.
• Pace your sending. Blasting hundreds of emails in a minute looks like spam to receiving servers. SecureMailMerge can add a delay between messages and cap how many are sent per day.
• Avoid spam triggers. Personalized individual emails already help; for the rest, see how to avoid landing in spam.

Frequently asked questions

What is the best way to send a mass email in Outlook?

For anything beyond a small internal group, a mail merge. It sends individual personalized emails, keeps your recipient list private, and tends to behave better with spam filters than BCC blasts.

How many people can I send a mass email to in Outlook?

Microsoft 365 work and school accounts are typically limited to 10,000 recipients per rolling 24 hours and 500 recipients per single message (500 is the default; admins can raise it). A mail merge sends one message per recipient, so the daily recipient limit is the one that matters. See the full breakdown of Outlook sending limits.

Can I send a mass email in Outlook for free?

Yes. Contact groups and BCC are built into every Outlook, and SecureMailMerge is free for non-commercial use with all features included. The Word-based mail merge additionally requires desktop Word with Classic Outlook as the default mail app.

Can recipients tell it was a mass email?

With a contact group or BCC, yes, immediately. With a mail merge, each recipient receives a normal individual email addressed only to them, personalized with their own data.