sendmail_wrapper.py is a script which can be installed in server systems without an own local mail server.
It acts as a replacement for
/usr/sbin/sendmail and forwards all local system emails (e.g. generated by cron) to a predefined external mail account.
It is compatible to the sendmail binary, but ignores all command line arguments like the recipient address.
The same setup could be accomplished basically also with other tools like with msmtp. But third party mail providers tend to block more and more system generated mails because of spam counter measures. One example is a mail header “From: root” or “To: root” which does not match the provider account address in the envelope headers. sendmail_wrapper patches these headers so that they conform to the configured third party mail provider and can be delivered.