Step-by-step guide for setting up an Office 365 (Microsoft 365) IMAP account

Email Accounts, IMAP Mail

Detailed Guide: Office 365 IMAP Setup

1. Prerequisites

Before starting, make sure:

  • You have an active Office 365 mailbox (usually ending in @yourcompany.com).
  • Your username (email address) and password are ready.
  • If your organization uses Multi-Factor Authentication (MFA), you will need an App Password (not your regular password) unless the client supports Modern Authentication (OAuth2).

2. IMAP & SMTP Server Settings

These are the official Office 365 mail server settings:

Incoming Mail (IMAP):

  • Server: outlook.office365.com
  • Port: 993
  • Encryption: SSL/TLS
  • Username: Your full email address (e.g., user@domain.com)
  • Password: Your account password or App Password (if MFA is enabled)

Outgoing Mail (SMTP):

  • Server: smtp.office365.com
  • Port: 587
  • Encryption: STARTTLS (sometimes shown as TLS/SSL)
  • Username: Your full email address
  • Password: Same as above

3. Enable IMAP (if needed)

  1. Log in to Outlook Web App.
  2. Go to Settings (⚙️) > Mail > Sync email.
  3. Under POP and IMAP, ensure IMAP is enabled.
    • Some organizations disable POP/IMAP by policy. If you don’t see the option, contact your admin.

4. Client Configuration (Examples)

Microsoft Outlook (desktop)

  1. Open Outlook → File → Account Settings → Add Account.
  2. Choose Manual setup or additional server types → POP or IMAP.
  3. Fill in:
    • Name: Your name
    • Email Address: user@domain.com
    • Account Type: IMAP
    • Incoming Server: outlook.office365.com (Port 993, SSL/TLS)
    • Outgoing Server: smtp.office365.com (Port 587, STARTTLS)
    • Username: Full email address
    • Password: (your password or app password)
  4. Click More Settings… → Outgoing Server tab → check My outgoing server (SMTP) requires authentication.
  5. Test settings → Finish.

Mozilla Thunderbird

  1. Open Thunderbird → Set up an account → Email.
  2. Enter name, email address, password.
  3. Click Manual config.
  4. Enter:
    • IMAP: outlook.office365.com, Port 993, SSL/TLS
    • SMTP: smtp.office365.com, Port 587, STARTTLS
    • Username: full email
  5. Click Done.

Apple Mail (Mac / iOS)

  1. Go to Settings → Mail → Accounts → Add Account → Other.
  2. Choose Add Mail Account.
  3. Enter name, email, password, and description.
  4. For incoming:
    • Host Name: outlook.office365.com
    • Username: full email
    • Password: (your password)
  5. For outgoing:
    • Host Name: smtp.office365.com
    • Username: full email
    • Password: (your password)
  6. Save.

5. Troubleshooting

  • Authentication issues: If MFA is enabled, create an App Password via your Microsoft 365 account security settings.
  • Cannot send mail: Double-check port 587 with STARTTLS is selected.
  • Organization blocks IMAP: You may only be able to use Outlook or clients that support Modern Authentication.

That’s it — your Office 365 account should now work with IMAP!