OFFICE 365 SMTP SETTINGS
| Setting | Value |
|---|---|
| Server Address | smtp.office365.com |
| Username | Your email address |
| Password | Your Office 365 Password |
| Port Number | 587 (With TLS) |
| Authentication | Required |
| Sending Limits | 10,000 recipients a day |
| Send Rate Limit | Approx 30 messages per minute via SMTP |
| Sending Limit Per Email | 500 recipients per email (extendable up to 1000 by the admin) |
If Multi-Factor Authentication (MFA) is enabled, you must use an app password instead of your regular password.
Microsoft recommends using OAuth 2.0 for modern authentication where possible (especially in custom applications or scripts).
How to Set Up Office 365 SMTP Settings
Setting up Office 365 SMTP requires configuring your email client or application with the correct server details and authentication.
How to Set Up Office 365 SMTP Settings
Follow these steps to configure Office 365 SMTP in Outlook or any email client:
- 1
Open your email client/app settings — In Outlook Desktop: go to File > Account Settings > Account Settings. Select your account and click Change. Then click More Settings > Outgoing Server tab.
- 2
Enable SMTP authentication — Check the box "My outgoing server (SMTP) requires authentication." Select "Use same settings as my incoming mail server."
- 3
Enter the Office 365 SMTP server details
- 4
Enter your Office 365 login credentials — Username: Your full Office 365 email address. Password: Your Office 365 password (or an App Password if Multi-Factor Authentication is enabled).
- 5
Save and test the configuration — Click Next, and Outlook will run a test. If successful, you'll see "Task completed" for both sending and receiving emails.
Common Issues & Quick Fixes for Office 365 SMTP
Authentication keeps failing
Double-check your username and password. If you're using MFA, generate an app password instead. Note: App Passwords only work if the admin allows them.
Emails aren't sending at all
Make sure you're on port 587 with TLS because port 465 (SSL) isn't supported in Office 365.
Microsoft blocked SMTP AUTH
Microsoft is phasing out basic authentication. Log in to your 365 admin center and confirm SMTP AUTH is enabled for the account you're using.
Emails are landing in spam
Add SPF, DKIM, and DMARC records to your domain. These little DNS entries tell email providers you're a legit sender.
Hitting sending limits
Office 365 caps you at 10,000 recipients per day. If you're running campaigns, you'll need a dedicated email sending platform to avoid throttling.
FAQs
My SMTP isn't working. What's the first thing I should check?
Nine times out of ten, it's either the wrong port/encryption or SMTP AUTH being disabled in your Microsoft 365 admin settings.
Can I blast out bulk emails through Office 365 SMTP?
Not really. Microsoft limits you to 10,000 recipients per day. For cold outreach or bulk campaigns, you'll want a proper sending service.
What's the deal with SMTP relay vs authenticated SMTP?
Authenticated SMTP: It requires you to log in with your Office 365 mailbox and send mail. The best part about this is that it works from anywhere. SMTP Relay: It lets devices or apps (like printers/scanners) send emails through your domain without needing a full mailbox login. It is usually set up with the Exchange Online connector and is often IP-based.
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