phpmailer Vs PHPMailer: My Windows and Linux server experience

Working on a client project in a distant country recently presented an interesting challenge.

They had a strict requirement, I needed to upload my progress every week so they could monitor the project in real-time. I agreed, though with some initial reluctance.

This setup quickly revealed unexpected bugs whenever I moved my code from my local development environment to the live server. One particular issue left me truly dumbfounded: the PHPMailer-powered "send mail" feature worked flawlessly on my local machine, but consistently threw errors on the live server.
After hours of intense debugging, I finally discovered the issue. My local setup, as I knew, ran on a Windows environment, while the live server operated on a Linux (Unix-based) system. The root of my problems stemmed from a fundamental difference in how these operating systems handle file names.
On Windows, you have the flexibility to name files and folders in various ways; "phpmailer", "PHPMailer", "PhpMailer", and the system treats them all as the same. However, Linux is case-sensitive. This means that "PHPMailer" is seen as entirely distinct from "phpmailer" or "PhpMailer". My code was referencing a folder with one capitalization, but the server expected another.

The solution was simple once identified: I had to rename the PHPMailer folder on the live server to match the exact capitalization used in my require statements. Once I changed it to PHPMailer, everything worked perfectly.

If you ever encounter similar "file not found" errors when deploying from a Windows to a Linux environment, always ensure your file and folder naming conventions are precise and consistent down to the capitalization. Adhering to conventional naming standards across both servers will save you countless hours of debugging and a lot of stress.