Problem: email sending functionality is flaky

[jrwdunham]

Current send email functionality implicitly expects an MTA. Need better configuration support for different deployment environments. Some potentially useful links:

• https://docs.pylonsproject.org/projects/pyramid_mailer/en/latest/
• https://github.com/JiscRDSS/archivematica/pull/35/files
• https://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-using-sdk-python.html