Which patter requires config object and client object for send mail functionality? I read a lot about them and there is none. So, unless you can name it, you are making stuff up.

It is not even about abstraction. I can write func send_mail(msg: str, subject: str, address: str, from: str, server: str, port: num, <following 20 config variables>) and have procedural code with same functionality.

Writing test for every getter and setter will not give you safety at all. This sort of test is completely pointless.