I had like to share my experience on free conventional software vs a paid tool.
I had issues with Time Machine especially with the email backups. the background story: I receive roughly 100-120 mails every day and my my Mailbox would fill up every other month. I use POP since then, thus making emails more of system dependent.
But the retrieval was damn complicated and time taking.
Later I used Mail Backup X. This is a paid tool. The 15 day free trial went pretty well. easily retrieval at the other side as well. Mail Backup X offers Mirror Backup option, that enables me to keep a copy of backup automatically to Ext. HD. That ends my dependency on the Mac’s performance.
Paid tools make your job much easier.