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How to Setup SMTP Relay in Office 365 - LazyAdmin
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Before we take a look at how to set up SMTP Relay in Office 365, I first want to explain to you the difference between SMTP Relay and Direct Send. Because both use the MX endpoint as an SMTP server address, but they both have their own use case. “Direct Send in Office 365 is used to deliver email to only your internal mailboxes.” But the advantage is Direct Send is that you can use it also for third-party applications and it doesn’t require a static IP address for authentication.
SMTP Relay vs Direct Send in Office 365 “Because both use the MX endpoint as an SMTP server address, but they both have their own use case.” Direct Send in Office 365 is used to deliver email to only your internal mailboxes. This means that you can’t scan a document and email it directly from the scanner to an external email address. You will need to scan it to your own mailbox, and in Outlook forward it to the external contact.
SMTP Relay on the other hand can be used to send emails directly to external contacts, but only from networks (public IP addresses) that you have defined. “Support externally hosted applications Yes No” If you can’t use port 25, then your only other options are SMTP Auth client submission, which uses OAuth for authentication, or a third-party tool like SMTP2GO. The advantage of this tool is that you can use different port numbers, like for example port 2525, or even port 80, and simply authenticate with a username and password.
“You don’t want to use a mailbox (with username and password) for this, but preferable an SMTP server that sends the mail for you.” The problem with SMTP Authentication these days is that we want to use MFA on all our Office 365 accounts. When we create a dedicated mailbox for sending emails, we still can’t authenticate (and secure) it properly. This is also the reason that Microsoft doesn’t support SMTH AUTH anymore for new tenants created after 2020.
“You don’t want to use a mailbox (with username and password) for this, but preferable an SMTP server that sends the mail for you.” The problem with SMTP Authentication these days is that we want to use MFA on all our Office 365 accounts. When we create a dedicated mailbox for sending emails, we still can’t authenticate (and secure) it properly. This is also the reason that Microsoft doesn’t support SMTH AUTH anymore for new tenants created after 2020.