We have several layers of spam and virus filtering.
- The first layer is Cisco Ironport. It filters all traffic coming to HMC mail servers and discards egregious spam and viruses. Once it has discarded egregious spam and viruses, Ironport quarantines messages that it suspects could be spam or junk messages. Once a day, it sends an email to your account listing the messages that have been quarantined. You can click on any message in the list to release it from quarantine. Optionally you can also place the sender's address on a whitelist so that future messages will not be quarantined.
- The second layer of filtering takes place on Office365 and Google Apps for Education. Each of these services provides additional spam and junk mail filtering at the individual account level. They usually quarantine suspected spam in a separate folder, called "Spam" on Google Apps and "Junk Mail" on Office365. On both services you can "train" the spam filters to improve recognition of spam.