My understanding is that an "application aware" backup must be done on a MS Exchange database in order to trigger MS Exchange to truncate transaction logs. Right now the database resides on the C drive, which is the system volume. I read this article that recommends a full server backup.
I don't want to buy an expensive Exchange backup program, but I would like to avoid backing up the entire C drive. The only possibility I can guess at is using some sort of Windows command to make Exchange commit/truncate the log files and then use Windows Backup to perform a file-level backup of the database folder. The solution I propose was not recommended by anyone online, so I suspect it is not safe.
I am willing to write scripts and scheduled tasks if necessary.