It's fine to report bugs here. :)
How do you know the mailbox is bugged, exactly?
Viewing post in Caliross, The Shapeshifter's Legacy comments
Yes, thats basically what happens, the page doesnt let me upload it as a comment, so here it is https://8ctogod.itch.io/caliross
Nope, i don't know how to use the debug tool. But i passed the mission two times and the first time the message appeared, just the second time i tried the mission from a save that was just after talking to lord kito at the start of the misión, where You have to talk whit a noble girl, a maid and lord kairos that the message refused to appear, and no matter how many times i tried to reedo the mission it never showed the message again.
Thanks for the help, at least it's good to know that My save file isn't broken
The other possibility is that one of the third party scripts messed up. I have one to store variables outside of savefiles, and I have noticed it rarely, and seemingly at random, messes with variables it isn't supposed to interact with, maybe that's the issue (as it "remembered" the time you received the message in the previous save).
Deleting the "MyProject" folder can fix those issues, but it's probably not worth the effort at this point (and it's not guaranteed that's the problem to begin with).
It happened to me too when I read the mails you get right after starting Chapter 2, I had already read them in a previous save but remembered that I missed a quest from CH1 so reloaded that, finished it, and then started Chapter 2 again, and then there was the new mail symbol but no messages in the unread mails section. What I did was go over to my read mails, and there they were already, so I just re-read them from there and it got fixed