I didn't think they were but I created an account: Firstname.Lastname@domain.com and could not access it (via webmail) with firstname.lastname@domain.com.

I tried this repeatedly to be sure.

When you try and create a duplicate mailname in Plesk, but with different capitalizations, you get the error:

"Unable to add new mail name: The mail name Firstname.Lastname is already in the domain"

Was it always this way and I'm just noticing it now, or did something change and it pass me by?

Thanks...

 

Webmail uses IMAP to access accounts.
I think there is a configuration option for the Courier-IMAP to ignore case; I dont have access to a Plesk machine to make sure.

With a default install of Plesk though, usernames for email are case sensitive - at least when using IMAP.

-J