Account for missing and invalid address headers

[seanthegeek]

Python began strict email address format verification by default in Python 3.13 and backported the changes for security reasons.

As a result, when an address header is not used or malformed, mail-parser will return [('','')] (issues #132 and #133)

To fix these issues while maintaining the security of the default strict=True option in email.utils.parseaddr and email.utils.getaddresses, the following changes were made to mail-parser:

• The existing constant ADDRESSES_HEADERS list now only includes headers that can contain multiple addresses
  • bcc
  • cc
  • reply-to
  • to
• A new constant ADDRESS_HEADERS list includes headers that can only contain one address
  • delivered-to
  • from
  • sender
• Header parsing is only attempted if the header exists and has a value (Closes Junk data returned for address headers that are not used #133)
• Headers in the ADDRESS_HEADERS list are parsed using email.utils.parseaddr instead of email.utils.getaddresses, returning a tuple instead of a list of tuples
• For headers in either list, if an invalid address header is detected, a string stating Invalid {} header is added to the defects list, where {} is the name of the header, and has_defects is set to True
• Invalid headers in the ADDRESS_HEADERS are parsed manually if email.utils.parseaddr considers the address invalid, in order to show the intent of the defect on mail clients (Closes An email address will not be parsed if the Real Name is also an email address #132)

Demo email 1

From: [email protected] <[email protected]>
To: [email protected]
Subject: Example Email

Hello world!

Demo 1 JSON output before the changes

{
  "from": [
    [
      "",
      ""
    ]
  ],
  "delivered-to": [
    [
      "",
      ""
    ]
  ],
  "cc": [
    [
      "",
      ""
    ]
  ],
  "body": "Hello world!",
  "to_domains": [
    "",
    "example.com"
  ],
  "reply-to": [
    [
      "",
      ""
    ]
  ],
  "subject": "Example Email",
  "bcc": [
    [
      "",
      ""
    ]
  ],
  "to": [
    [
      "",
      "[email protected]"
    ]
  ],
  "has_defects": false
}

Demo 1 JSON output after the changes

{
  "to": [
    [
      "",
      "[email protected]"
    ]
  ],
  "body": "Hello world!",
  "from": [
    "[email protected]",
    "[email protected]"
  ],
  "subject": "Example Email",
  "to_domains": [
    "example.com"
  ],
  "has_defects": true,
  "defects": [
    "Invalid from header"
  ],
  "defects_categories": []
}

Demo email 2

From: [email protected]
To: [email protected]
Subject: Example Email

Hello world!

Demo 2 JSON output before the changes

{
  "from": [
    [
      "",
      ""
    ]
  ],
  "delivered-to": [
    [
      "",
      ""
    ]
  ],
  "cc": [
    [
      "",
      ""
    ]
  ],
  "body": "Hello world!",
  "to_domains": [
    "",
    "example.com"
  ],
  "reply-to": [
    [
      "",
      ""
    ]
  ],
  "subject": "Example Email",
  "bcc": [
    [
      "",
      ""
    ]
  ],
  "to": [
    [
      "",
      "[email protected]"
    ]
  ],
  "has_defects": false
}

Demo 2 JSON output after the changes

{
  "to": [
    [
      "",
      "[email protected]"
    ]
  ],
  "body": "Hello world!",
  "from": [
    "",
    "[email protected]"
  ],
  "subject": "Example Email",
  "to_domains": [
    "example.com"
  ],
  "has_defects": false,
  "defects": [],
  "defects_categories": []
}

[seanthegeek]

Switched this to a draft because some attributes aren't working correctly. I'll look into this tomorrow.

[seanthegeek]

Fixed