Hi All - Here's our scenario.
Migrating from server A to server B. Server A is a proprietary system that uses LDAP queries for delivering email. Server B is a Postfix system configured to deliver email using LDAP queries, mirroring as closely as possible, Server A. In testing, the Postfix server appears to be processing a large majority of mail correctly but we keep running into 'edge cases' where Postfix fails on delivering an email that the original server is able to deliver successfully. We have tried tracking these edge case failures through the mail logs, and correcting them as we find them, but we still run into these cases here and there. What we would like to do, as a transitional state, is mimic the Sendmail failover relay to re-direct undeliverable email from the Postfix system to Server A. With Server A only handling emails redirected to it from the Postfix server, this would allow us to more easily identify the edge cases. We think we could do this using fallback transport but before we go too deep, we'd like to see if anyone else has tried that and if it's a good idea or if anyone has a better way to tackle that scenario. In our scenario, we would only use the fallback transport until we completed migrating to the new system. thanks in advance.
