The Filter property in Get Outlook Mail Messages allows you to set a filter for the messages to be retrieved from the specified mail folder.

Note that the Filter argument is for STRICT filters only. Meaning, wildcards and regex matches won’t work.

For example:

This filter retrieves messages received on the current month:

[ReceivedTime] >=' + Now.ToString("MM/01/yyyy") + "' AND [ReceivedTime] < '" + Now.AddMonths(1).ToString("MM/01/yyyy")+ "'"

This filter retrieves messages with the EXACT subject line ‘Manila Downtime Advisory’

[Subject]='Manila Downtime Advisory'

Click here for more filter arguments you can use.