TechMail uses aggregate safe lists, a feature of Microsoft Exchange Online (Microsoft 365 email). Periodically, the email addresses from your Safe Senders List are aggregated at the mail gateway—Exchange Online Protection (EOP). The mail gateway is where mail comes into TTU from the Internet. Only email addresses are aggregated and not domains.

Before aggregate safe lists, it was still possible for an incoming email message to be rejected for delivery even if the recipient had the sender added to their Safe Senders List. This was because the gateway servers (where initial junk filtering takes place) had no way of knowing about a user's Safe Senders List stored in their mailbox, and the gateway would reject potential junk email before it entered the TTU email system. With aggregate safe lists, this no longer happens.

Please be aware that a change to a TechMail user's safe list could take up to five hours to be reflected at the mail gateway. Once five hours have passed, having the email address on your Safe Senders List on the server will cause incoming messages from that address to be scored as -1 to ensure they end up in your Inbox. The only way such messages will go to your Junk Email folder is if your email client software is putting them there or if a rule is configured on your account to move them.

NOTE: Safe and blocked lists have no effect on outbound message delivery.