Django email backend for multiple ESPs (Python 3)

 Anymail integrates several transactional email service providers (ESPs) into
 Django, with a consistent API that lets you use ESP-added features without
 locking your code to a particular ESP.
 .
 It currently fully supports Amazon SES (requires python3-boto3), MailerSend,
 Mailgun, Mailjet, Mandrill (MailChimp transactional), Postal (self-hosted
 ESP, requires python3-cryptography), Postmark, SendinBlue, SendGrid, and
 SparkPost.
 .
 Anymail normalizes ESP functionality so it "just works" with Django's
 built-in `django.core.mail` package. It includes:
 .
   * Support for HTML, attachments, extra headers, and other features of
     Django's built-in email
   * Extensions that make it easy to use extra ESP functionality, like tags,
     metadata, and tracking, with code that's portable between ESPs
   * Simplified inline images for HTML email
   * Normalized sent-message status and tracking notification, by connecting
     your ESP's webhooks to Django signals
   * "Batch transactional" sends using your ESP's merge and template features
 .
 This is the Python 3 version of the package.