No single product has every feature a company needs. Third-party spam and archiving tools can fill the gaps in Exchange Online and Office 365 features.
Many organizations moving to Exchange Online do so to get rid of the shackles of third-party add-ons such as backup software, archiving tools, and the spam and malware prevention products commonly installed alongside Exchange. Sometimes, the core functionality Exchange Online offers doesn’t do everything an organization needs, and it needs to once again rely on third-party tools. Knowing how to implement those tools is important.