Uppercase alias in CC of response causing response email dropped

[InAnimaTe]

Prerequisites

• I have searched open and closed issues to make sure that the bug has not yet been reported.

  Closest I could find was Email address with different capitalization are not applied to the same alias #1562 (comment)

Bug report

Describe the bug
When replying to an email sent to alias A with an uppercase version of alias A in CC line, receive a "non-reverse aliases exist" email from simplelogin and the person in TO line (original sender) does not receive email.

Example:
Sender: bestbuy@wesuck.com sends to alias A: cooldude@slmail.me
Reply with:

• To: bestbuy@wesuck.com
• Cc: COOLDUDE@slmail.me

This scenario will cause both an email from Simplelogin warning about sending to a "non-reverse alias" and result in the intended recipient not receiving the email/response.

Expected behavior
Expect for Simplelogin to act case-insensitive and recognize COOLDUDE@slmail.me and cooldude@slmail.me are indeed the same alias/person/recipient.

Environment (If applicable):
Using Gmail with Simplelogin premium.

Additional context
I've received emails which included both an uppercase and lowercase version of my alias in the To line. Clicking reply-all, the uppercase variant sometimes (not sure when or why in how that's determined) gets included in the response Cc line, which causes this issue and my email to not arrive back to the sender.