The server requested authentication method unknown to the client

This issue may arise when creating database tables or connecting to MySQL server v8.x. The following workaround assumes you were installing WebMail Pro from Debian/Ubuntu repository, but may be useful when dealing with version 8.x of MySQL Server.

For manual installation, you should supply database credentials via admin interface. But for automated installations, such as those done via Debian/Ubuntu repository, database credentials used by WebMail Pro are stored in data/settings/config.json file:

"DBName": [
    "pro8afterlogic",
    "string",
    null,
    "The name of database in SQL server used" 
],
"DBLogin": [
    "pro8afterlogic",
    "string",
    null,
    "Login for SQL user" 
],
"DBPassword": [
    "PassHere",
    "string",
    null,
    "Password to access SQL database"
],

Run mysql from command line, and enter the following commands (with the above credentials supplied) :

ALTER USER 'pro8afterlogic'@'localhost' IDENTIFIED WITH mysql_native_password BY 'PassHere';
GRANT ALL PRIVILEGES ON pro8afterlogic.* TO 'pro8afterlogic'@'localhost';
FLUSH PRIVILEGES;

Now you should be able to connect to MySQL and create tables from admin interface of WebMail Pro.