envelopes.conn.SMTP is a wrapper for smtplib.SMTP that supports Envelope objects and is reusable. Envelope.send() is just a shorthand you can use if you don't c

envelopes.conn.SMTP is a wrapper for smtplib.SMTP that supports Envelope objects and is reusable. Envelope.send() is just a shorthand you can use if you don't care about reusing connections. For requests it's simpler to support top-level functions, since in general HTTP request is self-contained. Envelope (or email.mime.MIMEMessage) object isn't enough to send an e-mail - you need to know the SMTP host, port, creds and set up the connection. While it's certainly possible to write envelopes.send() function that'd internally create an Envelope object and send it (all based on the args the function gets) I don't think it's that crucial.