When a brms backup is performed on the AS/400/4/5 Domino (Notes Version R5), not all of the mail directories are backed up. For instance, LN404/notes/data/mail/xxx, where xxx is backed up automatically one day and not the next. We use brms for our standard backup.
If I perform a SAV, 7 objects are backed up, 62 are not saved. I discovered the problem when I went to perform a restore for a user at one of our locations. I could not find his *.nsf file anywhere on the backup, I checked a weeks worth of data and found that sometimes the entire folder xxx was not backed up, other days it was backed up, but most of the *.nsf files were missing for that particular location.
It definitely sounds as if the software is not working as designed. However, this is fairly complex considering the amount of configuration and customization that this process involves. Lotus AS/400 support is best on this.