Have someone in the communication function become the email editor, putting together a daily, tightly edited email bulletin with headlines and one-paragraph items summarizing all the separate emails others wanted to send. Each paragraph can then have a link to the full story elsewhere.
Advertising and marketing lay a strong foundation for perception of a brand, at least until people have contact with a company. Once people buy products or interact with company employees, their long-term impressions will be shaped by their experiences. Employees need to internalize the company brand or its image will suffer.