Using Have I Been Pwned API, this PHP software checks a list of emails against HIBP database and reports on emails found in the database. This is an easy way to check if a list of email has items in leaked user databases.
You need a local or online webserver to use this. Copy the files in a folder in www or htdocs, and it is ready to use. The base password is admin. Change this as soon as possible, especially if you use it on an online webserver.
In the req folder you find a settings.php file. Edit this to customize the program. You can turn off password protection, change language and this is where you set up your own email list too.
Put your email address list in the lists folder, then in the settings.php edit the $fileName variable to match the list file's name. Any txt file works, you do not have to format it any way, the only condition is that email addresses should be seperated somehow.
The password protection and language support is me overdoing it after it failed to be used at work and started planning to upload it here.