How to Configure Office 365 SMTP Relay

There are three ways you can setup SMTP Relay for Applications and multi-function devices using Office 365. All three options are elaborated here. Option 1 and Option 2 are configured within the application and devices. Option 3 are setup within the application/devices and within Office 365 Admin Centre.

Option1 – Client submission: Authenticate device or application directly with an Office 365 mailbox.

Smart Host:

Port: 587 TLS Enabled or Port 25


  • Send email to inside or outside of the organisation.
  • Send email from any devices or IP addresses.
  • Send email from any location


30 messages sent per minute, and a limit of 10,000 recipients per day.

Username: Azure AD username or and Azure AD Password

Option 2- Direct Send: Send mail directly from a printer or an application to Office 365

Smart Host: FQDN of the MX record of your domain.

SPF Record: v=spf1 ip4:<public IP address of registered domain> ~all

Port: 25


  • Uses Office 365 to send emails, but does not require a dedicated Office 365 mailbox.
  • Doesn’t require your device or application to have a static IP address. However, this is recommended if possible.
  • Doesn’t work with a connector; never configure a device to use a connector with direct send, this can cause problems.
  • Doesn’t require your device to support TLS.


  • Direct send cannot be used to deliver email to external recipients, for example, recipients with Yahoo or Gmail addresses.
  • Your messages will be subject to antispam checks.
  • Sent mail might be disrupted if your IP addresses are blocked by a spam list.
  • Office 365 uses throttling policies to protect the performance of the service.

Username: Any email address for one of your Office 365 accepted domains and Azure AD Password

Option 3 – Special Send Connector: Configure a connector to send mail using Office 365 SMTP relay

Smart Host: FQDN of the MX record of your domain.

SPF Record: v=spf1 ip4:<Public IP Address of registered domain> ~all

Port: 25

Username: Any email address for one of your Office 365 accepted domains and Azure AD Password


  • Office 365 SMTP relay does not require the use of a licensed Office 365 mailbox to send emails.
  • Office 365 SMTP relay has higher sending limits than SMTP client submission; senders are not bound by the 30 messages per minute or 10,000 recipients per day limits.


  • Sent mail can be disrupted if your IP addresses are blocked by a spam list.
  • Reasonable limits are imposed for sending.
  • Requires static un-shared IP addresses (unless a certificate is used).

Setting Up Option 3:


  1. Sign in to Office 365.
  2. Select Domains. Select the Domain e.g. Click Manage DNS and find the MX record. The MX record will have a POINTS TO ADDRESS value that looks similar to
  3. Make a note of the MX record POINTS TO ADDRESS
  4. Go to a MX recording finding web site and find the IP address of MX record using below steps.

Open Command Prompt from internet connected computer, Type


>Set q=mx

> where is your domain name.


  1. In Office 365, click Admin, and then click Exchange to go to the Exchange admin center.
  2. In the Exchange admin center, click mail flow, and click connectors. click the plus symbol +. On the first screen, choose the options From Your Organisation to Office 365, Click Next, and give the connector a name.
  3. On the next screen, choose the option By verifying that the IP address of the sending server matches one of these IP addresses that belong to your organization, and add the IP address of MX Record from step 1.
  1. Leave all the other fields with their default values, and select Save.
  2. Test the configuration, send a test email from your device or application, and confirm that it was received by the recipient.

About Raihan Al-Beruni

My Name is Raihan Al-Beruni. I am working as an Infrastructure Architect in Data Center Technologies in Perth, Western Australia. I have been working on Microsoft technologies for more than 15 years. Other than Microsoft technologies I also work on Citrix validated solution and VMware data center virtualization technologies. I have a Masters degree in E-Commerce. I am certified in Microsoft, VMware, ITIL and EMC. My core focus is on cloud technologies. In my blog I share my knowledge and experience to enrich information technology community as a whole. I hope my contribution through this blog will help someone who wants more information on data center technologies.
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