I actually sent an email (ironically enough!) to Corporate Comms the other day explaining that most operational staff (certainly at Heathrow) don't have time to log on to a computer to check their email account or read the intranet. In fact many don't even realise they have an email account.
That method might be fine for communicating with office staff who work at a computer desk, but the only way to be sure that ATCOs, ATSAs and ATCEs read any information is to leave a hard copy in the pigeonhole.