We've been working on a big mail management project (coming soon to http://logicalware.net/). For the project it was useful to us to have the behaviour that calling sendmail directly gives rather than calling through smtplib.

In this case we wanted to send mails on behalf of customers without reconfiguring our mail servers.

This product is only a few lines of code which changes the MailHost send method away from smtplib to sendmail.