[arrl-odv:23995] Duplicate copies of mail relayed from Microsoft Outlook

I'm receiving, for some number of weeks, *many* duplicate copies of e-mails sent from addresses similar to <MicrosoftExchange329e71ec88ae4615bbc36ab6ce41109e@arrl.org> Is anyone else experiencing this duplicate copy bombardment? What is the reason for these e-mails, and how do I arrange to no longer receive them? Thanks, Bob -- W6RGG