What are the SMTP settings for Outlook Office 365?
What are the outgoing SMTP server settings for Microsoft Office 365 for Business?


MXTools are often asked the outgoing SMTP settings for other ESP (Email Service Providers). This article discusses the outbound email settings for Microsoft's Office 365.

Service Provider Microsoft Office 365 (for business)

Protocol SMTP
Port 587
Authentication Required Yes

Useful Links


Some ISP's (Internet Service Providers) block you using their SMTP servers when you aren't connected to their network. MX Tools provides an outbound SMTP service that works from any network, any location called MX Outbound (MXO). MXO is an authenticated SMTP mail relay (SmartHost) service.

Some ISP's even block, filter or redirect standard SMTP (Port 25) traffic. So MX Tools provides alternative SMTP ports to use.

If you would like more information on MX Outbound (MXO) then click here.

  • Safe and Secure mail relay service
  • Authenticated SmartHost
  • Support for TLS/SSL
  • Alternative SMTP ports
  • Global coverage

Say goodbye to 550 SMTP relayed denied messages.