I'm glad this is fixed in new versions, let's hope our repo will eventually catch-up (in like 2025 :D ). Due to maintenance reasons, I had to make a workaround by making lowercase wrapper script for my "mailer" msmtp. This should work for both older and newer versions and once we get to >7.5.3 I don't need to fix it back. :) Thank you for your support and good work.
Not sure if this was reported but we noticed an issue with 7.4.3 in Ubuntu with mailer field in the config - before it executes, it makes the characters to lower case. This is not good practice in case you have capital letter switches, for example: msmtp -C ... is converted to msmtp -c ... and totaly breaks the command.