Office 365 SMTP Settings
Anant Gupta
If you use Office 365, reliable email delivery is a must—whether it’s for day-to-day correspondence, automated notifications, or connecting third-party tools.
But before anything can be sent, you need the right SMTP settings.
These details are the bridge between Office 365 and the outside world, making sure your emails reach their destination without a hitch.
Not sure where to start? We’re here.
SMTP configuration can seem technical at first glance, but with the right guidance, it’s surprisingly manageable.
This complete guide will walk you through everything you need to know: the key settings, common pitfalls, and best practices.
Let’s get your Office 365 email set up and running smoothly.
What is an Office 365 SMTP server
Office 365 SMTP is the “postman” for your emails.
When you want to send an email from an app, printer, or even another email client, SMTP is the standard way to get that message out the door.
With Office 365, the SMTP server handles your email.
First, it checks your login details. If everything is correct, it sends your message to the right inbox. This could be someone in your company or anyone else in the world.
In short: You or your device send the email to Office 365’s SMTP server.
The server checks your info. If it’s all good, your message gets delivered safely.
All behind the scenes, all pretty seamless—when it’s set up right!
We might need a graphic (Generated using TeamGPT)
Office 365 SMTP Email Sending Flowchart
- Start
↓ - App/Device/User creates an email
↓ - Connects to Office 365 SMTP server
↓ - Enters login credentials (username & password)
↓ - SMTP server checks credentials
├── If valid → continue
└── If not valid → authentication error (end)
↓ - SMTP server accepts the email
↓ - SMTP server processes the message
↓ - Delivers email to recipient’s mail server
↓ - Recipient’s mail server receives the email
↓ - Email appears in recipient’s inbox
Why should you use Office 365 as a SMTP server?
Here are a few reasons why using Office 365 as your SMTP server makes sense:
- Reliability: Office 365 is built to be dependable. Your emails are less likely to get lost or stuck.
- Security: It uses strong security features to protect your messages and help prevent unauthorized access.
- Easy Integration: If you’re already using Office 365 for your business email, connecting apps, printers, or websites is much simpler.
- Consistent Delivery: Office 365’s servers have a good reputation, which means your emails are less likely to end up in the spam folder.
- Support: Microsoft offers support and regular updates, so you don’t have to worry about keeping things up to date.
In short, using Office 365 as your SMTP server means your emails get delivered reliably, securely, and with less hassle.
How to configure Office 365 SMTP server settings?
Step 1: Check and Turn On SMTP AUTH
Before you can send emails using Office 365’s SMTP server, you need to make sure SMTP AUTH is enabled for your mailbox.
Here’s how to check:
Using the Exchange Admin Center (EAC):
- Sign in to the EAC with your admin account.
- Go to “Recipients” and then “Mailboxes.”
- Locate and select your mailbox.
- Look for the SMTP AUTH setting to see if it’s turned on.
Using PowerShell:
- Connect to Exchange Online PowerShell with your admin credentials.
- To see if SMTP AUTH is enabled, run:
Get-CASMailbox -Identity “user@domain.com” | Format-List SmtpClientAuthenticationDisabled |
- If this shows ‘False’, SMTP AUTH is on.
- If it shows ‘True’, SMTP AUTH is off.
- To enable SMTP AUTH, enter:
Set-CASMailbox -Identity “user@domain.com” -SmtpClientAuthenticationDisabled $false |
A couple of notes:
- Changes made in the EAC or PowerShell may take some time to apply.
- You’ll need admin access to check or change these settings.
Step 2: Add Office 365 SMTP Details
To send emails through Office 365, you’ll need to enter these settings in your app or email client:
- SMTP server: smtp.office365.com
- Port: 587 (recommended) or 25
- Encryption: TLS/StartTLS enabled
- Username: Your full email address (e.g., john.doe@yourcompanyname.com)
- Password: Your Office 365 password
Note: If you use multi-factor authentication (MFA), you’ll need to set up an app password for this connection.
How to Configure Office 365 POP3 settings?
After setting up Office 365 SMTP for sending emails, you’ll also need a way to pull or retrieve messages from your mailbox. POP3 (Post Office Protocol 3) is a common choice for this.
POP3 settings for Office 365:
To set up POP3, enter these details in your email app or client:
- Server: outlook.office365.com
- Port: 995
- Encryption: TLS/StartTLS enabled
- Username: Your full email address (e.g., john.doe@yourcompanyname.com)
- Password: Your Office 365 account password
- Select “See all settings” and go to the “Forwarding and POP/IMAP” tab.
- In the “POP Download” section, choose either “Enable POP for all mail” or “Enable POP for mail that arrives from now on,” based on your needs.
- Click “Save Changes” at the bottom.
- Open your third-party email client (like Outlook).
- When prompted for incoming mail server details, enter:
- Incoming Mail Server (POP): pop.gmail.com
- Port: 995
- SSL: Yes (required)
- Username: your full Gmail address
- Password: your Gmail password
- Server timeout: Set to more than 1 minute (5 minutes recommended)
- Display Name: your name
Following these steps will let you receive Gmail emails in your chosen email client using POP.
How to Configure Office 365 IMAP settings?
Many people prefer IMAP over POP3 because it keeps your messages synced across all your devices. Your emails stay on the server, so you can read, organize, and delete them from anywhere. It’s a lot like using cloud-based email.
IMAP settings for Office 365:
To set up IMAP, use these details in your email client:
- Server: smtp.office365.com
- Port: 993
- Encryption: TLS/StartTLS enabled
- Username: Your full email address (e.g., john.doe@yourcompanyname.com)
Password: Your Office 365 password
Frequently Asked Questions
Can I use Office 365 SMTP to send emails from a multifunction printer or scanner?
Yes, you can! Most printers and scanners that support SMTP can connect to Office 365’s SMTP server. Just use smtp.office365.com as the server, port 587, and enable TLS. You’ll need to provide a valid Office 365 username and password for authentication. (If your account uses MFA, you’ll need to create an app password.)
What authentication methods does Office 365 SMTP support, and does it require TLS?
Office 365 SMTP supports basic authentication (username and password) for SMTP AUTH, but Microsoft is encouraging the move to modern authentication. TLS encryption is required—this keeps your credentials and emails secure during transmission. Always use port 587 with STARTTLS/TLS enabled.
Are there daily or hourly sending limits when using Office 365 SMTP?
Yes, there are limits. For most Office 365 accounts, you can send up to 10,000 recipients per day. If you’re using SMTP AUTH, the limit is often 30 messages per minute and 10,000 recipients per day. If you hit the limit, your emails may be blocked temporarily.
Why are my emails sent via Office 365 SMTP being marked as spam or not delivered?
There are a few common reasons:
- The content or subject line triggers spam filters.
- Your “From” address doesn’t match the authenticated Office 365 user.
- Your domain’s SPF, DKIM, or DMARC records are missing or incorrect.
- You’re sending to too many recipients at once, or your emails look like bulk mail.
- The recipient’s email server has strict filtering rules.
Double-check your message content and your domain’s DNS records, and try sending a test email to a different address.
Is it possible to use Office 365 SMTP with legacy applications that do not support modern authentication?
Yes, but there are caveats. If your legacy app only supports basic authentication, you can use SMTP AUTH, but Microsoft is gradually disabling basic auth for security reasons. If your organization still needs it, an admin can enable SMTP AUTH for specific mailboxes. For accounts with multifactor authentication, you’ll need to use an app password. Long-term, it’s best to update your apps to support modern authentication methods.
