Before the implementation of Exchange Online, any email sent to an @cam address (or a managed mail domain address) was guaranteed to route through PPSW. The UIS Exchange Online service adds a complication to this.

Email originating outside the University's Exchange Online tenancy

For any mail that originates from outside Exchange Online, the email will flow through PPSW and on to its destination as before.

Email originating inside the University's Exchange Online tenancy

For email that originates within UIS' Exchange Online tenancy, Exchange will first look in its internal address book to see if there is a match.

If there is a match, the email will be sent to that Exchange mailbox.

If there is no match, the mail will be routed out of Exchange Online as normal.

Usually this is not an issue and people will not notice this change in behavior.

This change in behaviour will only be visible if the recipient, for whatever reason, has a mailbox both inside Exchange Online and elsewhere (e.g. Hermes). In this situation, email may seem to disappear as the user may be looking in the wrong mailbox.

Under normal circumstances, if a user has mailboxes in both Hermes and Exchange Online, UIS will ensure a forward is put in one of the mailboxes to point to the other. This typically occurs during a mailbox migration from Hermes to Exchange Online.

Occasionally, something goes wrong and the forwarding is not set up so the user notices that they are not receiving all their expected email. This is a rare event, however, and UIS strives to avoid this situation occurring.