Erik Oster contributed to this report. WPP has hired two outside law firms to investigate several anonymous, encrypted emails sent to its current and former employees, which came from a WhatsApp group that included onetime executive assistants to Martin Sorrell, the holding company’s founder and ex-CEO who abruptly stepped down in April, the Financial Times… https://www.adweek.com/agencies/wpp-hires-lawyers-to-probe-emails-sent-to-current-former-employees-following-sorrells-exit/