parsing a list of addresses returns empty set if there is an invalid email

[indrora]

Python 3.6.2 (v3.6.2:5fd33b5, Jul  8 2017, 04:57:36) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from flanker.addresslib import address
INFO:flanker.addresslib._parser.parser:building mailbox parser
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url_list' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'delim' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'url' is unreachable
INFO:flanker.addresslib._parser.parser:building addr_spec parser
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url_list' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'delim' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'url' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'angle_addr' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'name_addr' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'phrase' is unreachable
INFO:flanker.addresslib._parser.parser:building url parser
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url_list' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'delim' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'addr_spec' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'angle_addr' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'name_addr' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'phrase' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'local_part' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'domain' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'quoted_string' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'domain_literal' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'quoted_string_text' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'domain_literal_text' is unreachable
INFO:flanker.addresslib._parser.parser:building mailbox_or_url parser
WARNING:flanker.addresslib._parser.parser:Symbol 'mailbox_or_url_list' is unreachable
WARNING:flanker.addresslib._parser.parser:Symbol 'delim' is unreachable
INFO:flanker.addresslib._parser.parser:building mailbox_or_url_list parser
>>> address.parse_list('bob@example.net,steve@example.com')
[bob@example.net, steve@example.com]
>>> address.parse_list('bob@example.net,steve@example.com, potato')
[]

[horkhe]

Passing comma separated string to parse_list is an anti-pattern, because the ambiguity of grama does not allow reliably parse lists that contain garbage like this one. It is better pass a list of strings to parse_list when possible e.g.: address.parse_list(['bob@example.net','steve@example.com','potato'])

[indrora]

The documented behavior and observed behavior differ. It would probably make sense to update the documentation that indicates this is totally reasonable and supported, similarly with the API reference that indicates that this is allowed.

[horkhe]

You are right, the documentation needs to be updated. The comma separated string parser used to work kind of ok, before support for UTF-8 addresses was added. At that point grama became too ambiguous because we needed to support not only RFC valid addresses but also addresses that are technically invalid but de-facto used on the Internet. That made it difficult to distinguish whether a comma is an address separator or a part of an address.

[wedi]

I just stumpled upon such a case with an email from a law firm, where the From header looked like this:

From: =?UTF-8?Q?Argonaut_=7c_D=c3=bcmpling=2c_Giant_=26_Partner?= <mollusc@example.com>
<==>
From: Argonaut | Dümpling, Giant & Partner <mollusc@example.com>

parse_list() fails due to the comma:

Python 3.7.7 (default, Mar 10 2020, 15:43:03)
[Clang 11.0.0 (clang-1100.0.33.17)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from flanker.addresslib import address
>>> address.parse_list("Argonaut | Dümpling, Giant & Partner <mollusc@example.com>")
[]
>>> address.parse_list("Argonaut | Dümpling Giant & Partner <mollusc@example.com>")
[Argonaut | Dümpling Giant & Partner <mollusc@example.com>]

Is it reasonable/possible to add a non strict mode to parse_list() like parse() has?

>>> address.parse("Argonaut | Dümpling, Giant & Partner <mollusc@example.com>")
"Argonaut | Dümpling, Giant & Partner" <mollusc@example.com>
>>> address.parse("Argonaut | Dümpling, Giant & Partner <mollusc@example.com>", strict=True)
>>>