Question Where is the index.html for mail.domain-name.tld located?

[Arize]

Hey fellow pleskians,

I'm pretty new to plesk and started using it today. So far I really like it but I have one problem:
I found the default index.html files for my domains and replaced them. Then I randomly found out, that there is one default index.html left which is used for the subdomain "mail.domain-name.tld" and I can't find it via FTP nor putty. Do you guys have any idea where this file is located?

Thanks in advance!