If you are backing up to a local directory or S3 bucket whose path is based on the backup time, this option can be used to delete backups older than some number of days. This can be useful to reduce the amount of disk space needed to store old data.

However, this is only usable when the backup destination directory is named like `/backup/%d-%m-%Y`, or the filename is named like `/backup/virtualmin-%d-%m-%Y.tar.gz`. This is required for Virtualmin to be able to work out which files and directories were created by the backup process.

You must also check the box Do strftime-style time substitutions on file or directory name, or else date and time codes in the backup path will not be converted when the backup is run.

The maximum backup age is entered in days, but you can use fractions like 0.25 for four hours.