I would like to perform the same query except I would like to exclude all mailboxes which have a value in the custom attribute. Here is the command I used, but it didn't work: set-DynamicDistributionGroup WLCS -RecipientFilter { ((RecipientType -eq 'UserMailbox') -and -not(CustomAttribute1 -eq 'non-wlcs')) } When I preview the results, it shows the correct mailboxes, however, if I email that group, no one gets the email. Any idea where my problem is?

Hi,Please run the cmdlt below to verify if it will output the correct result.$WLCS = Get-DynamicDistributionGroup -id WLCSGet-Recipient filter $WLCS.recipientfilterBesides,I recommend you to check if there's any latency for DC replication.Regards,Xiu