For those not aware already, Lync is having some issues. Some customers appear to be reporting Exchange/outlook issues also.
Josh created a master ticket
Please link any related tickets the master ticket. – 0340057
https://helpdesk.oregonstate.edu/otrs/index.pl?Action=AgentTicketZoom&TicketID=336014
Any updates to the root cause or resolution, please put a note in that ticket.
Thanks.