On a recent imscp install we just found that some clients reveiced delivery notifications from the server for every mail they sent, either for success or for errors/delays.
They are complaining for an option they enabled in outlook (office.microsoft.com )
The problem is that they don't expect to receive so much mail and get annoyed by it, specially because the end recipient might accept sending the delivery notification. In that case for every mail the sender would receiv two different delivery notifications.
After reading about the topic, we decided to disable dsn in our system, some rationale about this:
.- Explanation about dsn in about.com (see Recipient extensions) about.com
.- In postfix you can't disable a part of dsn postfix.org so you have to either disable DSN altogether or live with it.
At the moment, in our install we've done:
What have you done in your environments?
