Thats correct. Kannel will always call the URL you provide to send you a DLR. The storage method is irrelevant in that respect.
okay, so i'm sorry if this sounds really bleeding obvious, and if it does it's because i've never dealt with astronomical volumes of messages but:
in a machine with (say) 1gb of RAM, and a dlr-url, and the fact that most smsc's don't tell you anything except the 'final' state of a message (and the fact that your messages generally get delivered pretty quickly as long as your smsc isn't complete shite)....
why does anyone use mysql or postgresql dlr-storage? i mean, does anyone, at any time, have more than, say, 100mb of dlr-storage? mysql/postres, they can handle TERABYTES of data, but, couldn't you handle a dlr-queue for a _telco_ with a peasant's budget worth of ram?
cheers iain
