Make Alias case insensitive like normal email addresses are

[Phiplex]

Most, or I would say all email addresses are case insensitive.

But SimpleLogin does not allow an alias to use upper case characters. I think it should. I for one always write a persons name in email addresses with normally the starting character as a capital letter, as in normal writing. For example my email address is [email protected]. (Phiplex being my first name and Domain being my family name.)

The case sensitivity of the local part in email addresses, as specified in RFC 5321 Section 2.3.11, is more of a theoretical possibility rather than a practical reality. Most mail servers treat email addresses as case-insensitive:

1. Historical and Practical Reasons
   • While RFC 5321 allows case sensitivity, most email systems chose to ignore it early on because:
   • It avoids confusion and user errors.
   • It simplifies email handling and prevents duplicate accounts (e.g., [email protected] and [email protected] would be seen as different, which could be problematic).
   • Popular email providers (like Gmail, Outlook, etc.) adopted case insensitivity, which became the de facto standard.

2. ASCII and Case Sensitivity
   • The ASCII standard (originally 7-bit) assigns different numerical values to uppercase and lowercase letters:
   • ‘A’ (0x41) vs. ‘a’ (0x61) → They differ by a single bit.
   • This means case-sensitive systems must explicitly check for case differences, while a case-insensitive system can simply normalize everything to lowercase before comparison.
   • Since many early email systems were implemented on case-insensitive operating systems (like Windows and some UNIX-based mail servers), treating email addresses as case-insensitive was easier.

3. Domain Names Are Always Case-Insensitive
   • RFC 1035 (which governs DNS) specifies that domain names are case-insensitive.
   • This consistency in DNS reinforced the idea of treating email addresses as case-insensitive as well.

4. Practical Implementation in Mail Servers
   • While RFC 5321 technically allows case sensitivity in the local part, it leaves it up to the receiving mail server to decide.
   • The overwhelming majority of mail servers today store and compare email addresses case-insensitively to avoid unnecessary complexity.

Conclusion

Even though ASCII theoretically allows case-sensitive differentiation, and RFC 5321 doesn’t prohibit it, practical considerations, user-friendliness, and historical implementations have made case insensitivity the norm in email systems.