Microsoft 365 SMTP setup

Prerequisites

• A Microsoft 365 Business account (not a personal outlook.com)
• Access to Microsoft 365 Admin Center, OR your IT admin to enable SMTP AUTH

Step 1: Enable SMTP AUTH for your account

SMTP AUTH is disabled by default on new Microsoft 365 tenants.

Option A, Admin enables for all users:

Go to admin.microsoft.com

Navigate to Settings > Org settings > Modern authentication

Ensure "Turn on modern authentication" is checked

Under SMTP, enable Authenticated SMTP

Option B, Admin enables per-user:

Go to admin.microsoft.com > Users > Active users

Select your user > Mail tab

Under "Email apps", click Manage email apps

Enable Authenticated SMTP

Save

Step 2: Configure in Revnox

Go to Settings > Email Accounts > Add Account:

• SMTP Host: smtp.office365.com
• Port: 587
• Security: STARTTLS
• Username: your full Microsoft 365 email address
• Password: your Microsoft 365 account password

Click Test Connection.

Daily sending limits

Microsoft 365 limits SMTP AUTH sends to 10,000 recipients/day per account. Revnox default is 200/day. Do not exceed 500/day without a fully warmed account.

Troubleshooting

If connection fails with "Authentication unsuccessful", SMTP AUTH is not enabled for your account. Contact your M365 admin. If connection fails with "TLS negotiation failed", verify Port 587 with STARTTLS (not SSL/Port 465).