What is EOES?

EOES, short for Enstrayed Orenco Email System, is the mail server that handles all mail for enstrayed.com.

Why did a message from @enstrayed.com end up in spam?

The short and oversimplified answer is that Email services provided by large tech coporations, such as Google (Gmail/Workspace) and Microsoft (Outlook/Exchange), attempt to fight spam by turning Email into an exclusive club. Only companies that pay them, or have enough money to pay people to negotiate with them, are allowed to freely send Emails to them.

The more nuanced answer is that they pretty much don't have a choice. Email is a very old standard, with its protocols being first introduced in the 1980s. There have been revisions and improvements since then, however these can only help so much. Because of this, fighting spam is a cat and mouse game, even moreso at the scale companies like Google and Microsoft deal with.