New EmailMessage attribute `envelope_sender` controls ESP's sender,
sending domain, or return path where supported:
* Mailgun: overrides SENDER_DOMAIN on individual message
(domain portion only)
* Mailjet: becomes `Sender` API param
* Mandrill: becomes `return_path_domain` API param
(domain portion only)
* SparkPost: becomes `return_path` API param
* Other ESPs: not believed to be supported
Also support undocumented Django SMTP backend behavior, where envelope
sender is given by `message.from_email` when
`message.extra_headers["From"]` is set. Fixes#91.
Django allows setting the reply address with either message.reply_to
or message.extra_headers["Reply-To"]. If both are supplied, the extra
headers version takes precedence. (See EmailMessage.message().)
Several Anymail backends had duplicate logic to handle conflicting
properties. Move that logic into the base Payload.
(Also prepares for common handling of extra_headers['From'], later.)
Related changes:
* Use CaseInsensitiveDict for processing extra_headers.
This is potentially a breaking change, but any code that was trying
to send multiple headers differing only in case was likely already
broken. (Email header field names are case-insensitive, per RFC-822.)
* Handle CaseInsensitiveDict in RequestsPayload.serialize_json().
(Several backends had duplicate code for handling this, too.)
* Fixes SparkPost backend, which had been incorrectly treating
message.reply_to and message.extra_headers['Reply-To'] differently.
[RFC-5322 allows](https://tools.ietf.org/html/rfc5322#section-3.6.2)
multiple addresses in the From header.
Django's SMTP backend supports this, as a single comma-separated
string (*not* a list of strings like the recipient params):
from_email='one@example.com, two@example.com'
to=['one@example.com', 'two@example.com']
Both Mailgun and SparkPost support multiple From addresses
(and Postmark accepts them, though truncates to the first one
on their end). For compatibility with Django -- and because
Anymail attempts to support all ESP features -- Anymail now
allows multiple From addresses, too, for ESPs that support it.
Note: as a practical matter, deliverability with multiple
From addresses is pretty bad. (Google outright rejects them.)
This change also reworks Anymail's internal ParsedEmail object,
and approach to parsing addresses, for better consistency with
Django's SMTP backend and improved error messaging.
In particular, Django (and now Anymail) allows multiple email
addresses in a single recipient string:
to=['one@example.com', 'two@example.com, three@example.com']
len(to) == 2 # but there will be three recipients
Fixes#60
* **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.
Compatibility with Python 2.7 versions older than 2.7.7
* Use Django's constant_time_compare method
* Include sparkpost in test requirements
* Don't use non-public `EnvironmentVarGuard` in tests
Fixes#41
Drop `from __future__ import unicode_literals`;
it was there for Python 3.2 compatibility (which
Anymail doesn't support). Ensures tests use normal
strs in Python 2.x.
When using a stored template, SparkPost disallows
subject, text, and html. Django's EmailMessage default
empty strings are enough to provoke "Both content
object and template_id are specified" from SparkPost,
so remove them (if empty) when using stored templates.
Update docs and tests; add integration test for template_id.
Fixes#24
python-sparkpost generates a transmissions.send
payload which is now considered invalid by the API,
if you try to use both `cc` (or `bcc`) and the
`recipients` dict structure required for merge_data.
[Anymail had been generating that recipients dict
structure in all cases, for simplicity. Sometime
between 2016-06-07 and 2016-06-22, SparkPost
began rejecting that if it appeared in the `header_to`
constructed by python-sparkpost.]
