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SMTP Direct Send - Knowledgebase / Office 365 - CTSi Group - Helpdesk

SMTP Direct Send

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Direct Send Method for Office 365

Another option to consider when setting up devices and LOB applications to send email messages is to use direct SMTP send. In this case, the device or application will handle all email delivery directly, regardless of destination, and Office 365 is not used to send the messages. There are several scenarios where this can be the best choice:

  1. If the device or application is only sending email to your own Office 365 users, then this is the simplest method, as there is absolutely nothing to configure.

  2. If the device or application has a built-in SMTP server capability and you want to manage and control it separately. This may be particularly useful if you don’t want Office 365 to throttle or scan your outbound email for viruses and spam.

  3. If you’re sending bulk email or newsletters, as Office 365 does not support this. You may want to enlist the help of a bulk email service provider to assist you. There are best practices that should be followed and bulk email providers are well-suited to ensure that your domains and IP addresses are not blocked by others on the Internet.


Mail delivery will only occur within the Office 365 domain.  Sending to external addresses is not permitted under the Direct Send model.

Use: TCP Port 25 - TLS Optional

No authentication is required.

We recommend adding an SPF record to avoid having messages flagged as spam. If you are sending from a static IP address, add it to your SPF record in your domain registrar’s DNS settings as follows:


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