This script normalizes email addresses based on a list of providers with known subaddressing or 'plus addressing' rules.
- The seperator sequence of the local-part of an emai address is dependent on the implementation of the mail server RFC 5233.
- There aren't any specific guidelines on the priority of comments vs. subaddressing in either RFC 5233 - Sieve Email Filtering: Subaddress Extension or RFC 5322 - Internet Message Format. From what I have experienced, some servers (ex. gmail) will consider everything after the subaddress identifier (ex. in gmail's it is '+') a subaddress of the local.
- Although RFC 5321 - Simple Mail Transfer Protocol says that "The local-part of a mailbox MUST BE treated as case sensitive" most mail servers default to a case insensitive local.
- Internationalized domains ought to be converted to punycode.
- When
--validate_emailis used, the provided email is validated against Django 3.1's email validator regex. This regex only allows a subset of valid email addresses according to the RFC 3696 - Application Techniques for Checking and Transformation of Names.
usage: normalizer.py [-h] --email EMAIL [--case-insensitive-local]
[--aggressive-subaddressing-removal] [--internationalized_domain]
[--validate_email]