Mailgun merges user-variables (metadata) into the webhook post data
interspersed with the actual event params. This can lead to ambiguity
interpreting post data.
To extract metadata from an event, Anymail had been attempting to avoid
that ambiguity by instead using X-Mailgun-Variables fields found in the
event's message-headers param. But message-headers isn't included in
some tracking events (opened, clicked, unsubscribed), resulting in
empty metadata for those events. (#76)
Also, conflicting metadata keys could confuse Anymail's Mailgun event
parsing, leading to unexpected values in the normalized event. (#77)
This commit:
* Cleans up Anymail's tracking webhook to be explicit about which
multi-value params it uses, avoiding conflicts with metadata keys.
Fixes#77.
* Extracts metadata from post params for opened, clicked and
unsubscribed events. All unknown event params are assumed to be
metadata. Fixes#76.
* Documents a few metadata key names where it's impossible (or likely
to be unreliable) for Anymail to extract metadata from the post data.
For reference, the order of params in the Mailgun's post data *appears*
to be (from live testing):
* For the timestamp, token and signature params, any user-variable with
the same name appears *before* the corresponding event data.
* For all other params, any user-variable with the same name as a
Mailgun event param appears *after* the Mailgun data.
* **Future breaking change:**
Rename all Anymail backends to just `EmailBackend`,
matching Django's naming convention.
(E.g., switch to "anymail.backends.mailgun.EmailBackend"
rather than "anymail.backends.mailgun.MailgunBackend".)
The old names still work, but will issue a DeprecationWarning
and will be removed in some future release.
(Apologies for this change; the old naming convention was
a holdover from Djrill, and I wanted consistency with
other Django EmailBackends before hitting 1.0.)
Fixes#49.
Allow custom MAILGUN_SENDER_DOMAIN in Anymail
settings. (Replaces need to use global esp_extra.)
Improve docs to cover cases where this is needed.
(esp_extra sender_domain is still supported for
overriding individual messages.)
Fixes#26.
* message.template_id to use ESP stored templates
* message.merge_data and merge_global_data
to supply per-recipient/global merge variables
(with or without an ESP stored template)
* When using per-recipient merge_data, tell ESP to use
batch send: individual message per "to" address.
(Mailgun does this automatically; SendGrid requires
using a different "to" field; Mandrill requires
`preserve_recipients=False`; Postmark doesn't
support *this type* of batch sending with merge data.)
* Allow message.from_email=None (must be set after
init) and message.subject=None to suppress those
fields in API calls (for ESPs that allow "From" and
"Subject" in their template definitions).
Mailgun:
* Emulate merge_global_data by copying to
recipient-variables for each recipient.
SendGrid:
* Add delimiters to merge field names via
esp_extra['merge_field_format'] or
ANYMAIL_SENDGRID_MERGE_FIELD_FORMAT setting.
Mandrill:
* Remove Djrill versions of these features;
update migration notes.
Closes#5.
