Forum Discussion
Some emails being routed to old mailboxes, one month after changing MX records
We have moved our email hosting from our old hosting provider to Office 365, however, we still receiving some emails on our old email provider. It doesn't look like a DNS replication issue as it has...
Some email systems, Exchange included, will perform an internal discovery for the recipient first and deliver mail locally, before even looking at the MX record. Depending on the system in use, you might have several options available to deal with this: remove the already migrated accounts, configure forwarding, change the delivery settings (in Exchange you change the domain type), etc.