Hi you can analyze the protocol logs if you had.
Office 365 smtp relay logs.
Microsoft 365 or office 365 smtp relay does not require the use of a licensed microsoft 365 or office 365 mailbox to send emails.
Before you attempt to create a connector be sure your account has the proper exchange online permissions.
Senders are not bound by the 30 messages per minute or 10 000 recipients per day limits.
Smtp simple mail transfer protocol is used when you set up an on premises multi function printer scanner fax or line of business lob application that needs to send email.
Then click on more settings outgoing server to set up your smtp settings.
If some or all of your mailboxes are in office 365 there are a few options available.
Microsoft 365 or office 365 smtp relay has higher sending limits than smtp client submission.
Office 365 smtp settings.
We would like to get these logs from exchange to see why those messages were sent from.
Here s how you can set up office 365 smtp settings.
To set up an smtp relay you must first create a connector in office 365 to accept smtp transactions.
This connector will receive smtp relay transactions from the application or device.
Mail to domains not hosted on office 365 will be delivered directly from the iis smtp server to the final destination it will not pass through the office 365 smtp servers.
We have a quite a few servers in the company that allow to relay smtp through our current exchange environment.
Smtp relay client smtp submission or direct send.
The smtp relay server that wants to relay mail to the office 365 mail infrastructure will need to provide credentials username password using the basic authentication protocol.