When creating a block, you may choose between blocking emails from an entire website (like “spam.com”) or an entire domain extension (aka a Top Level Domain, or TLD), like “.xxx” or “.org”.
Every website must have a domain extension, such as: “.org”, “.com”, or “.net”. Some of these domain extensions were created for specific purposes or niches (like “.xxx” being mostly for sexually explicit material), which may allow you to block large amounts of unwanted emails just by blocking a TLD. Blocking by domain extension is also useful for blocking emails from an entire country.
For example “.cn” is used by most Chinese websites, and thus if you don’t want to receive any emails from a Chinese-based website you should block the “.cn” TLD.
Note: If you choose to block a popular domain extension like “.com”, you will NOT receive emails from any site that ends in “.com”, such as Google.com, Facebook.com, Ebay.com, etc., so please be careful when creating these kinds of blocks.