Hi @bz,
You can integrate a Power Automate with your SharePoint list to achieve this. Here are the steps:
- Create a flow and select "When an item is created or modified" as trigger.
- add a condition and set when [column] is equal to 30, 60, or 90.
- add an action "send an email notification(V3)" under "True".
Hope this answer helps. Please let me if you still have any questions.
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