1

We are having SEVERE difficulties sending email from an on-premise Unitrends appliance to our IT department emails (same domain.) Unable to get email to send via direct send or Normal SMTP. Unitrends support has been working on it for weeks. I’ve asked the ISP to check port 25 and 587 and they are saying that port 25 is blocked and 587 is open. They will not open port 25. I’m thinking it’s a security setting in O365. Hoping someone can guide me to where to look in O365. We are sending from LAN through a Meraki MX95 via Comcast to O365.

5 Spice ups
2

Follow this, the account you use will have to be exempt from MFA but you can restrict it to your IP. No need for port 25.

3

I have read the article you sent numerous times. Can you tell me which option in that article I need to follow and how to make the MFA exemption in O365 ?

4

I’d guess option 1. Provide an account (username and password) to the appliance - not a named user, a service account. Make sure the account has SMTP enabled in EAC. Hopefully you’re using conditional access for MFA, in which case you’d need to modify the conditional access enforcing MFA and exclude the account from it (but remember to add a policy that requires your public IP for that account).

5

Before you begin, ensure that you have the necessary permissions. If you previously enabled per-user MFA, turn it off before enabling Security defaults. Additionally, consider using Conditional Access policies for more granular control1. For advanced scenarios, such as integrating with third-party directory services using Azure MFA Server, refer to the official documentation. Set up multifactor authentication for users - Microsoft 365 admin | Microsoft Learn

6

So I don’t have the correct licensing to enable conditional access policies. We have an email account that we use for things like this. It is a regular account, but does not actually belong to any one user. So I’m not sure if that makes it a “service account” or if something specific to the way it is setup makes it a service account. What I can confirm is that Security defaults is set to off, MFA is disabled on the account we are trying to use. Under email apps settings for that account, all types are enabled (MAPI, Exchange Web Services, Mobile, IMAP, POP3, Outlook on the web) and the web app mailbox policy is set to OwsMailboxPolicy-Default. I’ve asked Unitrends engineer to configure for port 587 and try sending again. Should we be using the smtp.office365.com or ourdomain-org.mail.protection.outlook.com?

7

Also under Settings>Mail Flow>Security, Turn off SMTP Auth protocol is unchecked. And Turn on use of legacy TLS clients is checked.