One has to wonder what type of legal requirement this satisfies.
It certainly wouldn’t hold up to the “beyond a reasonable doubt” standard for US criminal prosecution.
I’ve been exposed to “lit holds” for various document management system before and usually a third party such as Box or Microsoft can attest to the immutability of files placed under lit hold, and/or there is an audit trail to make sure the chain of custody is intact.
My firm requires screenshots. If the concern is that someone would bypass that, well, someone could bypass TeleMessage, too.