OWA’s Sweep Feature Uses Both Inbox and Sweep Rules

Outlook Sweep Works in Monarch Client Too

I’m not quite sure why Microsoft made a big thing about highlighting the support for sweep rules in the latest build of the Monarch (One Outlook) client. Unless it was a subtle way to emphasize that when Monarch replaces the current Outlook for Windows client, users will gain access to features like Sweep that Outlook for Windows doesn’t support. If so, the message was too subtle and it went right over my head at the time.

Sweep Options

OWA and Monarch are the only clients that support Sweep today. The idea is that you use Sweep to clean up your mailbox by “sweeping” unwanted items into somewhere like the Deleted Items folder. The options are straightforward (Figure 1). After selecting a message from someone that you want to “sweep” (the sender) you can:

1. Move all messages from the sender in the source folder to the destination folder (the default is Deleted Items, but you can choose any mailbox folder). OWA processes this request immediately and doesn’t create either an inbox or sweep rule.
2. Move all messages from the sender in the source folder to the destination folder. OWA moves any matching messages immediately and creates an inbox rule to move future messages.
3. Keep the latest message from the sender and move the rest from the source folder to the destination folder. This action creates a sweep rule.
4. Move matching messages older than 10 days from the source folder to the destination folder. This action also creates a sweep rule.

Because Exchange Online processes both inbox and sweep rules on the server, it doesn’t matter that other clients don’t support the Sweep feature.

Comparing Inbox and Sweep Rules

When I started looking at the Sweep feature, I wondered why the developers opted to use a mixture of inbox and sweep rules. The probable answer is that it saved time to reuse existing functionality (inbox rules) to handle the situation where a user wants to remove all items from a sender in a folder plus any future matching items that arrive into the mailbox (inbox).

The inbox rule generated for this option is simple. Here’s an example

Get-InboxRule -Mailbox James.Ryan | fl

Description                           : If the message:
                                       the message was received from 'Petri IT Knowledgebase'
                                        Take the following actions:
                                         delete the message
                                         and stop processing more rules on this message

Enabled                               : True
Identity                              : cad05ccf-a359-4ac7-89e0-1e33bf37579e\8434222137593561089
Name                                  : Messages from Petri IT Knowledgebase

While inbox rules process items as Exchange delivers them to the Inbox folder, Sweep rules can apply to any folder except Sent Items. That’s because the items in Sent Items come from the mailbox owner and it doesn’t make sense to clean up their own messages. It’s also not supported to create a sweep rule from an item in search results.

Sweep rules apply on a scheduled basis. In other words, a background Exchange assistant runs to execute the rules. Like all Exchange background assistants, the exact time when the process runs to sweep items out of a folder depends on its defined workcycle and the service load, so you can’t predict when item sweeping occurs.

Outlook Sweep Rules and PowerShell

An Exchange administrator can create sweep rules for mailboxes with PowerShell. A mailbox owner can use PowerShell to create rules for their own mailbox, but this hardly ever happens.

The New-SweepRule cmdlet creates a new sweep rule. This example moves items from the designated sender from the Inbox after seven days:

New-SweepRule -Enabled:$true -ExceptIfFlagged:$True -ExceptIfPinned:$True -KeepForDays 7 -Mailbox james.ryan@office365itpros.com -Name "Clean up Petri Seminars" -Provider Exchange16 -Sender Partners@petri.com

According to Microsoft documentation, the ExceptIfPinned and ExceptIfFlagged parameters are supposed to create exceptions for messages pinned to the top of the folder or flagged for some reason. Although I’ve included them in the command, New-SweepRule ignored the settings. Running Set-SweepRule to update the rule didn’t work either:

Set-SweepRule -Identity cad05ccf-a359-4ac7-89e0-1e33bf37579e\UIvh1A6dr0Cci8pYuUNHWA== -ExceptIfFlagged:$True -ExceptIfPinned:$True

Again according to the documentation, destination and source folders are identified using the normal Exchange notation of mailbox identity:\folder name (for instance, TonyR:\Archive). Both New-SweepRule and Set-SweepRule refused to accept any but deault folder destinations. These symptoms might be associated with the upgrade of older cmdlets to the V3 of the Exchange Online management module.

To complete this discussion, to remove a sweep rule, run the Remove-SweepRule cmdlet.

Remove-SweepRule -Identity cad05ccf-a359-4ac7-89e0-1e33bf37579e\YCfJ7ktCd0KNQuPqhtMAsg== -Confirm:$False

Outlook Sweep Removes Junk

The Sweep feature is an excellent way to remove service messages like Teams missed message notifications, newsletter updates, and other non-essential items from mailboxes. Of course, you could ignore any clean-up and depend on search to find messages when required, but it’s nice to get rid of some of the clutter that drops into mailboxes on an all too frequent basis these days.

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