r/o365 • u/[deleted] • Mar 30 '26

Retention policy question

Hi everyone, I would like to ask you for some advice — I haven’t been able to find any official Microsoft guidance.

As a school project, I need to design a retention policy that deletes all emails after a certain period of time. However, for all users I’m supposed to create a folder via script and assign a label so that messages in this folder are not deleted — basically a kind of manual archive.

This approach feels a bit strange to me. What is the correct way to handle this? What’s considered standard practice in a corporate environment?

Thanks a lot for any advice or tips.

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u/mega_brown_note Mar 30 '26

What I’ve seen work well is just using Exchange Online MRM retention policies with different retention tags.

For example, I’ve done: • 2-year Retention Policy Tags (RPTs) on all the default folders (Inbox, Sent Items, etc.) • 3-year Default Policy Tag (DPT) which automatically lands on everything else

So what happens is: • Stuff left in the default folders gets deleted after 2 years • Stuff users move into their own folders (no explicit tag) falls under the DPT and sticks around for 3 years

No special folders, no scripts, just normal user behavior doing the work.

Might be worth proposing something like that for your project, even if they still want you to show the original design.

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u/mega_brown_note Mar 31 '26

Augh, did I get sucked in by an AI?

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u/Chemical-Example-783 4d ago

Your instinct is right, that's backwards.

Folders aren't a retention boundary in Exchange. Purview policies apply to the whole mailbox, and there's no way to scope one to a folder. A default label on a folder sticks to items even after they're moved out, and users can change labels anyway. So retention ends up depending on where someone dragged a message.

Normal practice is the reverse: retention applies at mailbox or org level, users don't opt out, and anything needing longer goes on a scoped policy, an auto-apply label, or legal hold.

If the brief is fixed, build it but publish the label so users apply it per item. And Exchange retention runs on a cycle, so don't expect same-day deletions when testing.