Office 365 SMTP
Setting up a mailing profile with the Django SMTP backend fails when trying to send email via Office 365 (smtp.office365.com), due to Microsoft's strict requirements for the "From" field. See: https://stackoverflow.com/questions/48654081/django-send-mail-from-smtp-office365-com
This means that when trying to send an email via Office 365, the email is silently dropped on Microsoft's end.
The best method to resolve this would likely be adding a configurable "From" address to the mailers section. A less desirable, but likely easier method would be to use the value from the "Username" field in the "From" field.