This only applies to Classic DFFS in SharePoint Online / Microsoft 365
Microsoft is deprecating the SendEmail API on October 25, 2025 (https://support.microsoft.com/en-us/office/retirement-of-the-sharepoint-sendemail-api-b35bbab1-7d09-455f-8737-c2de63fe0821) and if you send emails from classic DFFS, this change means you’ll need to ensure that the checkbox “Use custom list with workflow to send E-Mails” option found in the E-Mail and Print tab is checked, and that you have set up the necessary FLOW to send the email.
The user manual is updated with instructions on how to build the FLOW, but you can also find the information here.
I recommend checking out Modern DFFS for SharePoint Online: https://spjsworks.com
Post any feedback below.
Alexander